Restore classic Join and Merge handlers, make index-based handlers optional

[florianesser]

Functionally identical to this hale-core PR

Restore the classes JoinHandler and PropertiesMergeHandler as the default handlers for the transformation functions Join, Groovy Join, Merge and Groovy Merge.

The previous default handlers IndexJoinHandler and IndexMergeHandler have demonstrated negative impact on the performance of some transformations. Until this is better understood and fixed, these handlers are now optional and can be activated via the following Java properties and environment variables:

• Join/Groovy Join: hale.functions.use_index_join_handler / HALE_FUNCTIONS_USE_INDEX_JOIN_HANDLER
• Merge/Groovy Merge: hale.functions.use_index_merge_handler / HALE_FUNCTIONS_USE_INDEX_MERGE_HANDLER

ING-4464

[github-actions[bot]]

This PR cannot be merged yet because a required label is missing: challenged. It needs to be added before this PR can be merged.

[github-actions[bot]]

hale studio builds for this pull request:

• Linux x64
• Windows x64
• macos x64

Build triggered for commit 8e61992d6ce5b0963dc9194e1b5f7ec89fdee009. Artifacts are retained for 14 days.

[florianesser]

/autosquash

[florianesser]

Merging w/o challenge as performance improvement was tested as part of the hale-core PR and verification of the functionality of the new switches is not essential.