analyses: Replace uses of namespacet::follow

[tautschnig]

This will be deprecated (see #8209). Use suitable variants of follow_tag instead.

• 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.
• n/a 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

Attention: Patch coverage is 78.00000% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 79.64%. Comparing base (08b2f2f) to head (7f7b10d).

Files	Patch %	Lines
src/analyses/custom_bitvector_analysis.cpp	0.00%	4 Missing ⚠️
src/analyses/invariant_propagation.cpp	0.00%	4 Missing ⚠️
src/analyses/invariant_set.cpp	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8215   +/-   ##
========================================
  Coverage    79.64%   79.64%           
========================================
  Files         1684     1684           
  Lines       195684   195705   +21     
========================================
+ Hits        155852   155869   +17     
- Misses       39832    39836    +4     

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