Merge changes from topics "revert-2629131-sandbox-rust-inputs-JRFPQTIPEY",...

Merge changes from topics "revert-2629131-sandbox-rust-inputs-JRFPQTIPEY", "revert-2758566-WBNIADIEXA" into main

* changes:
  Revert^3 "add rust_toolchain_rustc_prebuilt module type"
  Revert^3 "add crate_root property to rust modules"
  Revert^3 "allow Ninja variables in RuleBuilder API"
  Revert "conditionally escape rule builder command"
  Revert "support sandboxed rust rules"
  Revert "fix failing rust_aconfig_library test"
  Revert "rustSetToolchainSource to use linux-x86 srcs"
  Revert "remove rust deps on clang prebuilts"