fix: Harden "async" check for users with out-of-date sqlalchemy libraries

[alexander-beedie]

Closes #17022.

• Hardens async checks for sqlalchemy connections so they are resilient to old library versions (that do not actually implement any such support).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.02%. Comparing base (69e3824) to head (3ada45e).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17029      +/-   ##
==========================================
+ Coverage   81.00%   81.02%   +0.01%     
==========================================
  Files        1448     1448              
  Lines      190543   190551       +8     
  Branches     2722     2723       +1     
==========================================
+ Hits       154357   154393      +36     
+ Misses      35683    35655      -28     
  Partials      503      503              

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[stinodego]

Looks good to me, thanks!