Fix timestamp filtering in ZooKeeper registry causing pre-warmup failure

[funky-eyes]

What is the purpose of the change?

原代码逻辑是想去除timestamp，pid这种可变的值，剥离后生成出一串不可变的url作为key，进行缓存，避免该实例重启或重新注册到zk，可变值产生变化导致缓存失效，stringUrls中的缓存膨胀的问题，但是这样去除后，在loadbalance进行预热时，由于timestamp被过滤从而无法获取timestamp，导致预热功能失效。
以及修复源代码逻辑存在缺点，比如老的dubbox，dubbo2.6左右的版本存在remote.timestamp，default.remote.timestamp,该逻辑会导致假设url为remote.timestamp=xxxx&revision=xxxx
被过滤后就变成了remote.revision=xxxx，导致revision这个参数直接消失了。

The original logic intended to strip out variable fields like timestamp and pid from the URL, generating a stable, immutable string as the cache key. This prevents cache invalidation when an instance restarts or re-registers to ZooKeeper (due to changing values), and avoids cache bloat in stringUrls.
However, after removing these fields, during load balancing pre-warming, the absence of timestamp means it can no longer be retrieved, causing the pre-warming functionality to fail completely.
Additionally, the original logic has a flaw: in older Dubbo versions (e.g., DubboX or Dubbo 2.6), parameters such as remote.timestamp and default.remote.timestamp exist. When filtering removes timestamp, a URL like remote.timestamp=xxxx&revision=xxxx becomes remote.revision=xxxx, causing the revision parameter to disappear entirely.

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 55.10204% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 41.27%. Comparing base (c2df4ac) to head (d800fd4).

Files with missing lines	Patch %	Lines
...bo/registry/support/CacheableFailbackRegistry.java	55.10%	10 Missing and 12 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                3.2   #16033      +/-   ##
============================================
- Coverage     41.27%   41.27%   -0.01%     
- Complexity    10493    10496       +3     
============================================
  Files          1652     1652              
  Lines         71461    71492      +31     
  Branches      10163    10175      +12     
============================================
+ Hits          29499    29506       +7     
- Misses        37837    37850      +13     
- Partials       4125     4136      +11     

Flag	Coverage Δ
integration-tests	38.31% <51.02%> (-0.02%)	⬇️
samples-tests	36.33% <55.10%> (+0.07%)	⬆️

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