[CODE HEALTH] Fix more clang tidy warnings (member initialization)

[dbarker]

Contributes to #2053

Changes

• fix missing initialization clang-tidy warnings
• fix performance-unnecessary-value-param warning
• fix performance-enum-size warning
• fix modernize-use-nullptr warning
• fix modernize-use-bool-literals warnings

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

❌ Patch coverage is 56.25000% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.27%. Comparing base (676c9dc) to head (16c2398).

Files with missing lines	Patch %	Lines
ext/src/http/client/curl/http_operation_curl.cc	25.00%	3 Missing ⚠️
api/include/opentelemetry/baggage/baggage.h	66.67%	1 Missing ⚠️
exporters/otlp/src/otlp_http_exporter_options.cc	0.00%	1 Missing ⚠️
.../otlp/src/otlp_http_log_record_exporter_options.cc	0.00%	1 Missing ⚠️
...ters/otlp/src/otlp_http_metric_exporter_options.cc	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4270      +/-   ##
==========================================
+ Coverage   81.19%   81.27%   +0.09%     
==========================================
  Files         444      444              
  Lines       18880    18835      -45     
==========================================
- Hits        15328    15307      -21     
+ Misses       3552     3528      -24     

Files with missing lines	Coverage Δ
api/include/opentelemetry/trace/span_id.h	100.00% <100.00%> (ø)
api/include/opentelemetry/trace/trace_id.h	100.00% <100.00%> (ø)
...elemetry/exporters/otlp/otlp_grpc_client_options.h	100.00% <ø> (ø)
...exporters/otlp/otlp_grpc_metric_exporter_options.h	100.00% <ø> (ø)
...de/opentelemetry/exporters/otlp/otlp_http_client.h	100.00% <ø> (ø)
...emetry/exporters/otlp/otlp_http_exporter_options.h	100.00% <ø> (ø)
...rters/otlp/otlp_http_log_record_exporter_options.h	100.00% <ø> (ø)
...exporters/otlp/otlp_http_metric_exporter_options.h	100.00% <ø> (ø)
exporters/otlp/src/otlp_file_client.cc	70.38% <ø> (ø)
...ters/otlp/src/otlp_grpc_metric_exporter_options.cc	80.77% <ø> (+2.20%)	⬆️
... and 12 more

... and 2 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.