Move GOLANG_FIPS=1 back into tests:fips CI job

Enabling `GOLANG_FIPS=1` as part of the build process caused a build
failure in
https://gitlab.com/gitlab-org/omnibus-gitlab/-/jobs/11294885432:

```
    panic: opensslcrypto: can't enable FIPS mode for OpenSSL 1.1.1f  31 Mar 2020: FIPS_mode_set
	openssl error(s):
	error:0F06D065:common libcrypto routines:FIPS_mode_set:fips mode not supported
		../crypto/o_fips.c:22
goroutine 1 [running]:
crypto/internal/backend.init.0()
	crypto/internal/backend/openssl.go:77 +0x254
make: *** [Makefile:116: bin/gitlab-shell] Error 2
```

Author: stanhu

.gitlab-ci.yml

@@ -186,6 +186,7 @@ tests:fips:
     - .test-job
   variables:
     FIPS_MODE: 1
+    GOLANG_FIPS: 1
   script:
     - make test_fancy
 

Makefile

@@ -28,7 +28,6 @@ ifeq (${FIPS_MODE}, 1)
     # If the golang-fips compiler is built with CGO_ENABLED=0, this needs to be
     # explicitly switched on.
     export CGO_ENABLED=1
-    export GOLANG_FIPS=1
 
     # Go 1.19 now requires GOEXPERIMENT=boringcrypto for FIPS compilation.
     # See https://github.com/golang/go/issues/51940 for more details.