Move all pg_tde related tests into contrib/pg_tde

[jeltz]

While these tests test our changes to pg_waldump they are quite easy to overlook right now and where exactly should we draw the line? These tests are not something we ever want to upstream and in the future when we figure out how we want to make sure pg_waldump works with encrypted WAL we likely will want to have the tests for that solution in the same folder as our other tests anyway.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.38%. Comparing base (e355f38) to head (796ff9a).

❌ Your project status has failed because the head coverage (78.38%) is below the target coverage (90.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           TDE_REL_17_STABLE     #269      +/-   ##
=====================================================
+ Coverage              78.34%   78.38%   +0.04%     
=====================================================
  Files                     22       22              
  Lines                   2484     2484              
  Branches                 391      391              
=====================================================
+ Hits                    1946     1947       +1     
  Misses                   462      462              
+ Partials                  76       75       -1     

Components	Coverage Δ
access	79.35% <ø> (ø)
catalog	86.23% <ø> (ø)
common	92.50% <ø> (ø)
encryption	71.90% <ø> (ø)
keyring	72.07% <ø> (ø)
src	54.12% <ø> (+0.33%)	⬆️
smgr	98.01% <ø> (ø)
transam	∅ <ø> (∅)

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