Rename Strategy.lr_schedulers to Strategy.lr_scheduler_configs

[akihironitta]

What does this PR do?

Addresses #11443 (comment)

No need to update the changelog since strategy hasn't been released yet?

Does your PR introduce any breaking changes? If yes, please list them.

• Strategy.lr_schedulers is renamed to Strategy.lr_scheduler_configs.

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cc @Borda @rohitgr7 @akihironitta

[codecov]

Codecov Report

Merging #11549 (e310573) into master (92c22ae) will decrease coverage by 4%.
The diff coverage is 93%.

❗ Current head e310573 differs from pull request most recent head f7ccd54. Consider uploading reports for the commit f7ccd54 to get more accurate results

@@           Coverage Diff            @@
##           master   #11549    +/-   ##
========================================
- Coverage      92%      88%    -4%     
========================================
  Files         194      194            
  Lines       16947    16947            
========================================
- Hits        15562    14948   -614     
- Misses       1385     1999   +614     

[carmocca]

LGTM!

I'd say we should add this to the CHANGELOG as "Changed"

[Borda]

any depreciation via property?