freetype: add package_type + fix check of custom CMake variables in test package

[SpaceIm]

same fix than #16389 (comment), but for test package of freetype.

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• I've read the contributing guidelines.
• I've used a recent Conan client version close to the currently deployed.
• I've tried at least one configuration locally with the conan-center hook activated.

[SpaceIm]

This PR has been triggered again because there are existing changes in master branch that are related to these same references resulting in different recipe-revisions. The build is being triggered on the PR context in case some additional fix is needed after merging those changes.

@danimtb @uilianries c3i reported successful build of this PR both in v1 & v2 pipelines 5 days ago. Now there is this message while there was 0 modification of freetype in master branch in the meantime, nor in any dependency of freetype. I see also that continuous-integration/jenkins/pr-merge is now silently marked failed 😞

[prince-chrismc]

v2 is running happily so far :)

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 7 (4f43acacf3145cc82f2047f9b1bc9f5536fc5fcd):

• freetype/2.13.0@:
  All packages built successfully! (All logs)

• freetype/2.12.1@:
  All packages built successfully! (All logs)

• freetype/2.11.1@:
  All packages built successfully! (All logs)

• freetype/2.10.4@:
  All packages built successfully! (All logs)

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Conan v2 pipeline (informative, not required for merge) ✔️

Note: Conan v2 builds are informative and they are not required for the PR to be merged.

All green in build 6 (4f43acacf3145cc82f2047f9b1bc9f5536fc5fcd):

• freetype/2.13.0@:
  All packages built successfully! (All logs)

• freetype/2.12.1@:
  All packages built successfully! (All logs)

• freetype/2.11.1@:
  All packages built successfully! (All logs)

• freetype/2.10.4@:
  All packages built successfully! (All logs)