In the previous ticket SERVER-93976, we migrated to Ruff and removed obsolete linting tools (pydocstyle, pylint, yapf). During the migration, we added multiple rule ignores in `pyproject.toml` to maintain compatibility. Now we need to:
1. Remove unnecessary rule ignores
2. Fix the corresponding issues in the codebase
 
possible rules we can remove (need to do more research on this list)

• `E712` (comparison-to-true) - Replace `== True` with `is True`
• `F541` (f-string-without-placeholders) - Remove unnecessary f-strings
• `F821` (undefined-name) - Fix undefined variable references
• `F841` (unused-variable) - Remove unused variables
• `PLR1711` (unnecessary-return) - Remove redundant returns
• `W291` (trailing-whitespace) - Remove trailing whitespace
• `W293` (blank-line-contains-whitespace) - Clean blank lines
• `W605` (invalid-escape-sequence) - Fix invalid string escape sequences