pdl: Remove rustfmt from no_alloc test

The no_alloc backend used rustfmt for an intermediate file generated
as part of a unit test. We plan to remove this backend, so the
formatting of this file is not critical.

Tag: #refactor
Bug: 274187738
Test: atest pdl_rust_noalloc_le_test
Change-Id: I3c7739a7c7ceeb447aa1b82890ec62d5c0e87276