Fix race condition with deprecation warnings (#9060)
Fix race condition with deprecation warnings (#9060)

### Problem

As reported in https://github.com/pantsbuild/pants/issues/9057, `warn_or_error` is not concurrency safe due to us mutating the `warnings` module. 

This mutation was used to allow passing multiple context lines to `warnings.warn_explicit()`, rather than the default of 1 line of context. For example, if `context=0`, we would render `<no code context available>`.

### Solution

Stop parameterizing `context=`. Turns out, this parameter was not exposed to any other deprecation functions like `deprecated_conditional`. There are also no call sites changing the default of `context=1`.

By removing the `context` parameter, we can rely on the default behavior of `warnings.warn_explicit()` to show one line of context, as determined by the `stacklevel` parameter.

### Result

Things stay the same for end-users. Will close https://github.com/pantsbuild/pants/issues/9057. 

```
▶ ./v2 list src/python/pants/util/strutil.py
Scrubbed PYTHONPATH=/Users/eric/DocsLocal/code/projects/pants/src/python: from the environment.
01:52:32 [WARN] /Users/eric/DocsLocal/code/projects/pants/src/python/pants/engine/legacy/parser.py:177: DeprecationWarning: DEPRECATED: Using `globs`, `rglobs`, and `zglobs` will be removed in version 1.27.0.dev0.
  Using deprecated `globs` in src/python/pants/util/BUILD at line 145. Instead, use a list of files and globs, like `sources=['f1.py', '*.java']`. Specify excludes by putting an `!` at the start of the value, like `!ignore.py`.

We recommend using our migration script by running `curl -L -o fix_deprecated_globs_usage.py 'https://git.io/JvOKD' && chmod +x fix_deprecated_globs_usage.py && ./fix_deprecated_globs_usage.py src/python/pants/util`
  self.check_for_deprecated_globs_usage(token_str, filepath, lineno)
```

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