Remove GradInformation module, including from LightningModule hierarchy

[ananthsub]

What does this PR do?

This module was deprecated in v1.3 and is slated for removal in v1.5. There's a dedicated utilities file which can be used for this instead. This simplifies the lightning module class dependencies

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

This removes the GradInformation module which was previously deprecated in v1.3

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[codecov]

Codecov Report

Merging #8831 (79f8646) into master (6de66eb) will decrease coverage by 4%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #8831    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         176     175     -1     
  Lines       14412   14402    -10     
=======================================
- Hits        13353   12762   -591     
- Misses       1059    1640   +581