Remove expand_depth in compile transform and max_expansion in clifford_t_decomposition transform

[andrijapau]

Context:

Completing the deprecation cycle of expand_depth in compile transform and max_expansion in clifford_t_decomposition transform.

Description of the Change:

1. Update deprecations.rst
2. Update changelog-dev.md
3. Remove all deprecated source code

No references found in Catalyst, Lightning, or QML.

[sc-77499]

[lillian542]

Looks good to me! 🚀

[mudit2812]

Very minor comment, otherwise LGTM

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.29%. Comparing base (e710ca6) to head (8decad4).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6531      +/-   ##
==========================================
+ Coverage   99.17%   99.29%   +0.12%     
==========================================
  Files         456      457       +1     
  Lines       43254    43413     +159     
==========================================
+ Hits        42899    43109     +210     
+ Misses        355      304      -51     

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