Handle URLs with invalid characters

[lloeki]

What does this PR do?

Handle additional URL corner cases.

Motivation

Fixes #2309

Additional Notes

Not entirely sure about the expected placeholder behaviour but it's an undocumented feature.

How to test the change?

Specs.

[codecov-commenter]

Codecov Report

Merging #2311 (46c2fc0) into master (f5984e8) will decrease coverage by 0.04%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2311      +/-   ##
==========================================
- Coverage   97.58%   97.54%   -0.05%     
==========================================
  Files        1094     1076      -18     
  Lines       57400    56765     -635     
==========================================
- Hits        56015    55369     -646     
- Misses       1385     1396      +11     

Impacted Files	Coverage Δ
...iling_native_extension/native_extension_helpers.rb	96.15% <ø> (ø)
...ontrib/sidekiq/server_internal_tracer/heartbeat.rb	36.00% <0.00%> (-28.00%)	:arrow_down:
...datadog/tracing/contrib/utils/quantization/http.rb	83.11% <0.00%> (-4.56%)	:arrow_down:
lib/ddtrace/transport/http/env.rb	92.85% <0.00%> (-3.58%)	:arrow_down:
...adog/core/configuration/agent_settings_resolver.rb	96.75% <0.00%> (-2.60%)	:arrow_down:
lib/datadog/core/diagnostics/environment_logger.rb	98.41% <0.00%> (-1.59%)	:arrow_down:
lib/datadog/core/configuration/settings.rb	98.41% <0.00%> (-0.53%)	:arrow_down:
spec/support/container_helpers.rb	99.55% <0.00%> (-0.45%)	:arrow_down:
...ng/contrib/active_support/cache/instrumentation.rb	87.58% <0.00%> (-0.09%)	:arrow_down:
lib/datadog/core.rb	87.50% <0.00%> (ø)
... and 27 more

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