buildBazelPackage: cleanup hacks and enforce them for all builds

[abbradar]

Motivation for this change

Timestamp verification skip is no longer needed (not sure why). Generally we
better off always using the environment hack for all packages because that
ensures all NIX_* flags are correctly applied.

One possible improvement in future is to filter only NIX_* variables to
passthru in Bazel.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

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@Profpatsch you may also be interested in reviewing this one too.

[Profpatsch]

cc @uri-canva @kalbasit

[uri-canva]

Yep, saw this as part of #64716, looks good to me.

[kalbasit]

@GrahamcOfBorg build bazel-watcher bazel-deps