Updates oss-fuzz to correctly parse Pigweed's updated CIPD JSON format
to fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=44445. Also
restores bloaty to the list of required CIPD packages to allow
post-bootstrap checks to pass.
Pigweed python env setup now uses the "arm-none-eabi-gcc" toolchain
to derive some flags for the newly added clang for ARM toolchain.
Bug: https://crbug.com/oss-fuzz/30513
Do not run example fuzzers in pw_fuzzer as those are for demonstration
purposes.
Test: run `python infra/helper.py build_fuzzers pigweed` and observe
pw_fuzzer/toy_fuzzer in pw_fuzzer is NOT copied to out directory.
armandomontanez