SOLR-17686: Rename stageInEnglish to stageToString and make it protected and non-static

[jeanielamwh]

https://issues.apache.org/jira/browse/SOLR-17686

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[cpoerschke]

Thinking about how the changes in this PR might be described in solr/CHANGES.txt ...

... so the user with a custom component with a custom distributed stage is still left in a "must have and configure a custom SearchHandler that overrides the stageInEnglish method" scenario ...

... might overriding be supported and yet could the base implementation use something like "CUSTOM_42" for a custom stage with value 42?

And looking at how the stageInEnglish method is called, perhaps

  private static boolean checkLimitsBefore(
      SearchComponent c,
-     String when,
+     Supplier<String> when,
      SolrQueryRequest req,
      SolrQueryResponse resp,
      List<SearchComponent> components) {

could also be considered i.e. for stageInEnglish to be only actually called when a limit is exceeded?

[jeanielamwh]

... might overriding be supported and yet could the base implementation use something like "CUSTOM_42" for a custom stage with value 42?

I like this idea. Otherwise, it seems a bit excessive to me that a user with custom stages must override this method that's used for logging only.

Pushed be8e468 to replace the throw with returning CUSTOM_STAGE_<NUM>. What do you think?

[dsmiley]

If we're going to expose this, I'd like to take the opportunity to reconsider this method name to not include the word "English". stageToString would be better IMO.
Otherwise, LGTM

[dsmiley]

Way too advanced/obscure to waste people's time mentioning in CHANGES.txt IMO.

[cpoerschke]

How about dropping the next prefix?

Suggested change

	protected String stageToString(int nextStage) {
	protected String stageToString(int stage) {