remove OSMesa (#9708)

* remove OSMesa

OSMesa is depricated for quite a while and got removed with Mesa 25.1.0

* remove OSMesa from all buildfiles, readmes, etc…

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Co-authored-by: Noisyfox <timemanager.rick@gmail.com>

doc/How-to-build.md

@@ -172,7 +172,6 @@ All required dependencies will be installed automatically by the provided shell
 - libgstreamerd-3-dev
 - libsecret-1-dev
 - libwebkit2gtk-4.0-dev
-- libosmesa6-dev
 - libssl-dev
 - libcurl4-openssl-dev
 - eglexternalplatform-dev