Optimize decode for Llama3-70B for TG for stable branch (#37360)

### Problem description
Improve the decode TPS for Llama3-70B on Galaxy for stable branch

### What's changed
Increased the core count for paged SDPA

### Checklist

- [ ] [![All post-commit
tests](https://github.com/tenstorrent/tt-metal/actions/workflows/all-post-commit-workflows.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/all-post-commit-workflows.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ] [![Blackhole Post
commit](https://github.com/tenstorrent/tt-metal/actions/workflows/blackhole-post-commit.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/blackhole-post-commit.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ]
[![cpp-unit-tests](https://github.com/tenstorrent/tt-metal/actions/workflows/tt-metal-l2-nightly.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/tt-metal-l2-nightly.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ] New/Existing tests provide coverage for changes


#### Model tests

If your changes cover model-related code, you should run tests
corresponding to affected models and platforms (Single card, T3K,
Galaxy). "Choose your pipeline" workflows facilitate running multiple
kinds of tests in a single run. Each offers `models-mandatory` and
`models-extended` presets.
The former includes a minimal set of tests, to be run always. The latter
extends that with additional ones - use your best judgement in deciding
which is the most appropriate for your PR.

- [ ] [![(Single) Choose your
pipeline](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ] `models-mandatory` preset (runs: [Device perf
regressions](https://github.com/tenstorrent/tt-metal/actions/workflows/perf-device-models.yaml)
and [Frequent model and ttnn
tests](https://github.com/tenstorrent/tt-metal/actions/workflows/fast-dispatch-full-regressions-and-models.yaml))
- [ ] `models-extended` preset (runs: the mandatory tests, plus
[Demo](https://github.com/tenstorrent/tt-metal/actions/workflows/single-card-demo-tests.yaml)
and [Model
perf](https://github.com/tenstorrent/tt-metal/actions/workflows/perf-models.yaml)
tests)
  - [ ] other selection - specify runs

- [ ] [![(T3K) Choose your
pipeline](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select-t3k.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select-t3k.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ] `models-mandatory` preset (runs: [Unit
tests](https://github.com/tenstorrent/tt-metal/actions/workflows/t3000-unit-tests.yaml))
- [ ] `models-extended` preset (runs: the mandatory tests, plus
[Demo](https://github.com/tenstorrent/tt-metal/actions/workflows/t3000-demo-tests.yaml)
and [Model
perf](https://github.com/tenstorrent/tt-metal/actions/workflows/t3000-model-perf-tests.yaml)
tests)
  - [ ] other selection - specify runs

- [ ] [![(Galaxy) Choose your
pipeline](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select-galaxy.yaml/badge.svg?branch=atupe/llama-70b-tg-optimizations)](https://github.com/tenstorrent/tt-metal/actions/workflows/pipeline-select-galaxy.yaml?query=branch:atupe/llama-70b-tg-optimizations)
- [ ] `models-mandatory` preset (runs: [Quick
tests](https://github.com/tenstorrent/tt-metal/actions/workflows/galaxy-quick.yaml))
- [ ] `models-extended` preset (runs: the mandatory tests, plus
[Demo](https://github.com/tenstorrent/tt-metal/actions/workflows/galaxy-demo-tests.yaml)
and [Model
perf](https://github.com/tenstorrent/tt-metal/actions/workflows/galaxy-perf-tests.yaml)
tests)
  - [ ] other selection - specify runs

Author: atupe-tt

models/demos/llama3_70b_galaxy/tt/model_config.py

@@ -1173,9 +1173,9 @@ def prefill_xqkv_minimal_matmul_config(seq_len):
             )
 
             self.model_config["PAGED_SDPA_DECODE_PROGCFG"] = ttnn.SDPAProgramConfig(
-                compute_with_storage_grid_size=(8, 4),
+                compute_with_storage_grid_size=(8, 6),
                 sub_core_grids=ttnn.num_cores_to_corerangeset_in_subcoregrids(
-                    self.start_core, 32, self.sub_core_grids, row_wise=True
+                    self.start_core, 48, self.sub_core_grids, row_wise=True
                 ),
                 exp_approx_mode=False,
                 q_chunk_size=0,