ci: unify run-*-examples-from-readme.sh into single entrypoint with TLS support

[atharvalade]

Which issue does this PR close?

Closes #2907

Rationale

Seven per-language scripts duplicated 60 to 70 percent of their logic (server startup, README parsing, teardown) and TLS example tests were missing for several SDKs. A single entrypoint that uses shared utilities and supports TLS addresses both issues.

What changed?

The six run-*-examples-from-readme.sh scripts and examples/node/test-examples.sh were replaced by scripts/run-examples-from-readme.sh, which sources shared helpers from scripts/utils.sh. Server lifecycle, README parsing, and example execution are centralized. The script accepts a --language flag (rust, go, node, python, java, csharp, or all) and runs both plain and TLS examples when available. CI calls the unified script for each language. The server is always built from source via cargo build, not from DockerHub.

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

• Opus 4.6
• Exploration and Review
• Minimal
• Yes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.26%. Comparing base (3f651e0) to head (20bf731).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2920      +/-   ##
============================================
- Coverage     70.27%   70.26%   -0.02%     
  Complexity      862      862              
============================================
  Files          1028     1028              
  Lines         85279    85279              
  Branches      62656    62665       +9     
============================================
- Hits          59932    59922      -10     
- Misses        22833    22835       +2     
- Partials       2514     2522       +8     

Flag	Coverage Δ
csharp	67.45% <ø> (-0.17%)	⬇️
go	36.37% <ø> (ø)
java	59.87% <ø> (ø)
node	91.37% <ø> (-0.15%)	⬇️
python	81.43% <ø> (ø)
rust	70.64% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 11 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[atharvalade]

pls check integration::mod connectors::mongodb::mongodb_sink::no_writes_performed_label_path_preserves_state_accuracy it's a flaky MongoDB integration test

[hubcio]

@atharvalade for now ignore flaky mongo connector test, i'll take care about it later today. lets merge this PR after #2898 - can you make sure that go TLS is also tested?