feat: add enable_pull_mode variable to make pull mode optional

[HectorQuiroz]

Description

Add optional enable_pull_mode variable to allow users to disable PULL mode integration when only PUSH mode (metric stream) is needed.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

Please delete options that are not relevant.

• My commit message follows conventional commits
• My code is formatted to Go standards
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes. Go here for instructions on running tests locally.

How to test this change?

Please describe how to test your changes. Include any relevant steps in the UI, HCL file(s), commands, etc

• Test 1: Verify PULL mode is created by default (backwards compatibility)
• Test 2: Verify PULL mode can be disabled
• Test 3: Verify existing deployments continue to work

[CLAassistant]

All committers have signed the CLA.