Temporarily revert #6876

[tautschnig]

As much as we would like to get rid of __CPROVER_allocated_memory, we don't currently have a replacement available. This PR removes the deprecation warning to reduce the noise for users who intentionally use this intrinsic. This is a clean revert of the two commit of #6876, and these two commits should be added back once we have a replacement.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (e02fd74) 78.94% compared to head (dfe0d89) 79.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7918      +/-   ##
===========================================
+ Coverage    78.94%   79.00%   +0.06%     
===========================================
  Files         1697     1697              
  Lines       195379   195370       -9     
===========================================
+ Hits        154242   154357     +115     
+ Misses       41137    41013     -124     

Files	Coverage Δ
src/ansi-c/goto_check_c.cpp	91.16% <ø> (-0.08%)	⬇️

... and 8 files with indirect coverage changes

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