bazel: builds on windows use /DEBUG:FASTLINK instead of /DEBUG:FULL

[ThadHouse]

/DEBUG:FASTLINK is deprecated in VS 2026, and hasn't been faster since VS 2019, and is actually slower.

[AustinSchuh]

Looks like Bazel will automatically test for if the flag is supported, and not use it if it isn't. So at least that will work. Slower is a good point and worth fixing.