* fix: resolve http.request placeholders in header directive find operation
- Skip regex compilation during provision when placeholders are detected
- Compile regex at runtime after placeholder replacement
- Preserves performance for static regexes while enabling dynamic placeholders
- Fixes#7109
* test: add tests for placeholder detection in header replacements
- Test containsPlaceholders function edge cases
- Test provision skips compilation for dynamic regexes
- Test end-to-end placeholder replacement functionality
