[POC] Record default metrics and logs for XdsBootstrap

[jrhee17]

Motivation:

Explain why you're making this change and what problem you're trying to solve.

Modifications:

• List the modifications you've made in detail.

Result:

• Closes #. (If this resolves the issue.)
• Describe the consequences that a user will face after this PR is merged.

[github-actions]

🔍 Build Scan® (commit: bf502d3)

Job name	Status	Build Scan®
build-ubicloud-standard-16-jdk-8	✅	https://ge.armeria.dev/s/vicv5e43fg73y
build-ubicloud-standard-16-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/mbgjg3im5ubei
build-ubicloud-standard-16-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/t22dqhmhx34zi
build-ubicloud-standard-16-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/d5i2pyeedpx2u
build-ubicloud-standard-16-jdk-17-leak	✅	https://ge.armeria.dev/s/gscevfn2emlmi
build-ubicloud-standard-16-jdk-11	✅	https://ge.armeria.dev/s/ioqq45ucr4jyq
build-macos-latest-jdk-21	✅	https://ge.armeria.dev/s/7x5gpnmeecl2e

[codecov]

Codecov Report

❌ Patch coverage is 80.16878% with 94 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.24%. Comparing base (8150425) to head (bf502d3).
⚠️ Report is 226 commits behind head on main.

Files with missing lines	Patch %	Lines
.../com/linecorp/armeria/xds/XdsBootstrapBuilder.java	16.66%	20 Missing ⚠️
...a/internal/client/DefaultClientRequestContext.java	52.63%	3 Missing and 6 partials ⚠️
...a/xds/DefaultXdsLoadBalancerLifecycleObserver.java	94.37%	6 Missing and 3 partials ⚠️
...ain/java/com/linecorp/armeria/xds/StatContext.java	0.00%	7 Missing ⚠️
.../com/linecorp/armeria/xds/ClusterResourceNode.java	45.45%	5 Missing and 1 partial ⚠️
...ain/java/com/linecorp/armeria/xds/WatcherUtil.java	0.00%	6 Missing ⚠️
...com/linecorp/armeria/xds/AbstractResourceNode.java	66.66%	5 Missing ⚠️
...eria/xds/DefaultConfigSourceLifecycleObserver.java	91.93%	3 Missing and 2 partials ⚠️
...com/linecorp/armeria/xds/ListenerResourceNode.java	54.54%	5 Missing ⚠️
.../linecorp/armeria/xds/ResourceNodeMeterBinder.java	82.14%	5 Missing ⚠️
... and 10 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6464      +/-   ##
============================================
- Coverage     74.46%   74.24%   -0.22%     
- Complexity    22234    23089     +855     
============================================
  Files          1963     2071     +108     
  Lines         82437    86623    +4186     
  Branches      10764    11319     +555     
============================================
+ Hits          61385    64316    +2931     
- Misses        15918    16905     +987     
- Partials       5134     5402     +268     

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