Remove default for stripped option, don't strip by default on android

[gmackall]

This is round 3, after #50443 and #51394. I think this is finally the right place to make the change, if this gn actually works.

Always respect the stripped argument if it is passed, but otherwise default to not stripping on android, and stripping on other platforms.

Still need to do some testing before landing, but making the PR so that this stays on my radar

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide and the C++, Objective-C, Java style guides.
• I listed at least one issue that this PR fixes in the description above.
• I added new tests to check the change I am making or feature I am adding, or the PR is test-exempt. See testing the engine for instructions on writing and running engine tests.
• I updated/added relevant documentation (doc comments with ///).
• I signed the CLA.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.