Convert String Formatting to f-strings with Flynt

[TimPansino]

Overview

• Run flynt linter to replace %, .format, and .join style string formatting with f-strings.
• Additional manual conversions done as follow up commits.

Note: There still exist quite a few % style string interpolations. They're used for the following:

• Lazy logging string interpolation for performance
• Byte string interpolation, only used in a few tests
• Very few select spots, particularly where constant templates are later interpolated with variable data.
  • Can be searched for loosely with this regex search in vscode or grep ['"]\s*(%|\.format)

Testing

Final flynt command used, which can be run for validation:

flynt -ll 999 -a -tc -tj ./ --exclude newrelic/packages/

[github-actions[bot]]

🦙 MegaLinter status: ❌ ERROR

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
❌ PYTHON	bandit	120		8	22.78s
✅ PYTHON	black	374	161	0	28.61s
❌ PYTHON	flake8	374		217	10.53s
✅ PYTHON	isort	374	193	0	1.14s
❌ PYTHON	pylint	374		755	96.53s

See detailed report in MegaLinter reports _Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff_

_MegaLinter is graciously provided by _

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 70.28754% with 93 lines in your changes missing coverage. Please review.

Please upload report for BASE (develop-remove-python27@3173305). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
newrelic/core/application.py	16.66%	20 Missing :warning:
newrelic/api/transaction.py	50.00%	16 Missing :warning:
newrelic/core/agent.py	7.69%	12 Missing :warning:
newrelic/network/addresses.py	0.00%	4 Missing :warning:
newrelic/bootstrap/sitecustomize.py	0.00%	3 Missing :warning:
newrelic/api/graphql_trace.py	0.00%	2 Missing :warning:
newrelic/common/object_names.py	50.00%	2 Missing :warning:
newrelic/core/config.py	81.81%	2 Missing :warning:
newrelic/core/profile_sessions.py	0.00%	2 Missing :warning:
newrelic/hooks/application_gearman.py	0.00%	2 Missing :warning:
... and 27 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop-remove-python27 #1200 +/- ## ========================================================== Coverage ? 81.43% ========================================================== Files ? 196 Lines ? 21487 Branches ? 3743 ========================================================== Hits ? 17499 Misses ? 2872 Partials ? 1116 ```

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