Make check for temporary table owned by other backend idiomatic

[jeltz]

Instead of doing it our own way do the way the rest of the code does it.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.49%. Comparing base (506606f) to head (a36b58b).

❌ Your project status has failed because the head coverage (80.49%) 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     #353   +/-   ##
==================================================
  Coverage              80.49%   80.49%           
==================================================
  Files                     22       22           
  Lines                   2604     2605    +1     
  Branches                 398      399    +1     
==================================================
+ Hits                    2096     2097    +1     
  Misses                   430      430           
  Partials                  78       78           

Components	Coverage Δ
access	82.95% <ø> (ø)
catalog	87.55% <ø> (ø)
common	91.80% <ø> (ø)
encryption	75.47% <ø> (ø)
keyring	72.00% <ø> (ø)
src	66.74% <ø> (ø)
smgr	97.29% <ø> (+0.02%)	⬆️
transam	∅ <ø> (∅)

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