[ci] Create an issue when loadtests fails

[paulojmdias]

Description

Adds a notify-failure job that creates a GitHub issue when load tests fail. Includes dedup check, performance results table, test failure output, and failed job names.

Load tests are currently failing and will be fixed in another PR.

Link to tracking issue

Relates to #46670

Testing

Tested locally against a real failed run (run ID 23989057509).

Sample issue body output

Auto-generated report for load-tests workflow.

Link to failed build: https://github.com/open-telemetry/opentelemetry-collector-contrib/actions/runs/23989057509
Commit: 90753d1

Component(s)

testbed

Failed jobs

• loadtest (TestTraceNoBackend10kSPS|TestTrace1kSPSWithAttrs)

Performance results

# Test PerformanceResults
Started: Sat, 04 Apr 2026 22:43:51 +0000

Test                                    |Result|Duration|CPU Avg%|CPU Max%|CPU Limit|RAM Avg MiB|RAM Max MiB|RAM Limit MiB|Sent Items|Received Items|
----------------------------------------|------|-------:|-------:|-------:|--------:|----------:|----------:|------------:|---------:|-------------:|
TraceNoBackend10kSPS/NoMemoryLimit      |FAIL  |     13s|   120.6|   121.0|     0.0|         45|         96|          0|     22600|         22590|CPU consumption is 121.0%, max expected is 90%
TraceNoBackend10kSPS/MemoryLimit        |FAIL  |     23s|   113.6|   113.6|     0.0|         33|         97|          0|     18510|         18490|CPU consumption is 113.6%, max expected is 90%
Trace1kSPSWithAttrs/0*0bytes            |PASS  |     15s|    20.0|    23.0|     0.0|         66|         94|          0|     15000|         15000|
Trace1kSPSWithAttrs/100*50bytes         |PASS  |     15s|    56.2|    58.7|     0.0|         71|        100|          0|     14990|         14990|
Trace1kSPSWithAttrs/10*1000bytes        |PASS  |     15s|    40.0|    42.0|     0.0|         70|         99|          0|     14990|         14990|
Trace1kSPSWithAttrs/20*5000bytes        |PASS  |     15s|    51.9|    53.3|     0.0|         75|        105|          0|      1830|          1830|

Total duration: 97s

Test failures

--- FAIL: TestTraceNoBackend10kSPS (36.02s)
    --- FAIL: TestTraceNoBackend10kSPS/NoMemoryLimit (13.02s)
    --- FAIL: TestTraceNoBackend10kSPS/MemoryLimit (23.01s)
FAIL
FAIL	github.com/open-telemetry/opentelemetry-collector-contrib/testbed/tests	97.421s

Note: Information about any subsequent build failures that happen while this issue is open, will be added as comments with more information to this issue.

[paulojmdias]

@songy23, I added the missing code to comment on an open issue if it is still open on subsequent failures.