Make CryptoService tests use a more obviously fake key for tests

[dpwatrous]

The current value looks too much like a real secret. Switched to a more obviously fake string.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.25%. Comparing base (90c2715) to head (eb1a204).

❗ Current head eb1a204 differs from pull request most recent head e1605c1. Consider uploading reports for the commit e1605c1 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2895   +/-   ##
=======================================
  Coverage   67.25%   67.25%           
=======================================
  Files        1259     1259           
  Lines       34187    34187           
  Branches     6291     6291           
=======================================
  Hits        22992    22992           
  Misses      11032    11032           
  Partials      163      163           

Files	Coverage Δ
...ient/core/secure-data-store/crypto-service.spec.ts	100.00% <100.00%> (ø)

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