cmake_package_config_generate: Fix CMake warnings with CMake 3.23

[Arfrever]

Correct syntax to run CMake built-in command-line tools is cmake -E:
https://cmake.org/cmake/help/v3.23/manual/cmake.1.html#run-a-command-line-tool

This test was mistakenly using cmake env ... cmake ..., where env and second cmake were interpreted as paths (of source directory or build directory), resulting in "Ignoring extra path from command line" CMake warnings with CMake 3.23.

Warnings in verbose test log (${glob_build_dir}/Testing/Temporary/LastTest.log) may look in this way:

CMake Warning:
  Ignoring extra path from command line:

   "${glog_build_dir}/test_package_config/working_config/env"


CMake Warning:
  Ignoring extra path from command line:

   "/usr/bin/cmake"

This type of cmake warning was originally introduced by cmake commit eacf1f879b0933509efbd4fb4d6d72ce99412aa7.

[codecov-commenter]

Codecov Report

Merging #792 (79790d7) into master (9f0b7d3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #792   +/-   ##
=======================================
  Coverage   72.78%   72.78%           
=======================================
  Files          17       17           
  Lines        3259     3259           
=======================================
  Hits         2372     2372           
  Misses        887      887           

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[sergiud]

Thank you!