Fix the provider.go imports

[modular-magician]

This now matches what is currently used in the file and used in the generated terraform provider.go files

As of now when you run the bundle command as described in the contributing section (https://github.com/GoogleCloudPlatform/magic-modules#generating-downstream-tools) it generates code with the following errors:

make build
==> Checking source code against gofmt...                                                                                                                                                                            
==> Checking that code complies with gofmt requirements...                                                                                                                                                           
go generate  ./...                                                                                                                                                                                                   
go install                                                                                                                                                                                                           
# github.com/hashicorp/terraform-provider-google-beta/google-beta                                                                                                                                                    
google-beta/provider.go:4:2: imported and not used: "encoding/json"                                                                                                                                                  
google-beta/provider.go:10:2: imported and not used: "github.com/hashicorp/terraform-plugin-sdk/v2/terraform"                                                                                                        
google-beta/provider.go:831:43: undefined: context                                                                                                                                                                   
google-beta/provider.go:1328:28: undefined: context                                                                                                                                                                  
google-beta/provider.go:1335:70: undefined: version
google-beta/provider.go:1346:32: undefined: time                                                          
google-beta/provider.go:1508:47: undefined: context                                                       
make: *** [GNUmakefile:9: build] Error 2      

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).

• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
  There are a few unrelated files that are broken and a lot of already existing lint errors.

• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).

• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).

• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

Derived from GoogleCloudPlatform/magic-modules#4700