try_compile: Do not use CMAKE_BUILD_TYPE or CMAKE_CONFIGURATION_TYPES env vars

Since:

* commit e216b9bb (cmake: Allow CMAKE_BUILD_TYPE to be set by
                     environment variable, 2021-06-29, v3.22.0-rc1~503^2~1)
* commit ef56eefc (cmake: Allow CMAKE_CONFIGURATION_TYPES to be set by
                     environment variable, 2021-06-29, v3.22.0-rc1~503^2)

the environment variables are supposed to provide defaults for settings
the user otherwise can control via cache entries.  However, they
accidentally affect `try_compile` projects too, which are supposed to be
programmatically controlled.

Fixes: #22935
36 jobs for !6755 with env-init-configs in 61 minutes and 6 seconds (queued for 3 seconds)
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