chore: pin terraform versions in CI

[lukemassa]

what

Add a script to add versions.tf to all test dirs that pin all necessary providers; run the script.

why

Help with CI stability if providers are pinned.

Adding a script means that we can easily bump all versions simultaneously in the future if we need to.

tests

Ran CI.

references

close #4484.

[chenrui333]

works for me.

[chenrui333]

            <details><summary>Show Output</summary>
            
            ```
            running "/usr/local/bin/terraform init -input=false" in "/tmp/TestSimpleWorkflow_terraformLockFileModified_.terraform.lock.hcl_triggers_autoplan_1120627109/001/repos/runatlantis/atlantis-tests/2/default": exit status 1
            
            Initializing the backend...
            
            Initializing provider plugins...
            - Reusing previous version of hashicorp/null from the dependency lock file
            ╷
            │ Error: Failed to query available provider packages
            │ 
            │ Could not retrieve the list of available versions for provider
            │ hashicorp/null: locked provider registry.terraform.io/hashicorp/null 3.1.0
            │ does not match configured version constraint 3.2.2; must use terraform init
            │ -upgrade to allow selection of new versions
            ╵

caused some test failure, https://github.com/runatlantis/atlantis/actions/runs/9470306781/job/26091248454

[chenrui333]

missed lockfile update 😅

atlantis/server/controllers/events/testdata/null_provider_lockfile_old_version

Lines 4 to 6 in 7999e1c

	provider "registry.terraform.io/hashicorp/null" {
	version = "3.1.0"
	constraints = "3.1.0"

[chenrui333]

            <details><summary>Show Output</summary>
            
            ```
            running "/usr/local/bin/terraform init -input=false" in "/tmp/TestSimpleWorkflow_terraformLockFileModified_.terraform.lock.hcl_triggers_autoplan_1120627109/001/repos/runatlantis/atlantis-tests/2/default": exit status 1
            
            Initializing the backend...
            
            Initializing provider plugins...
            - Reusing previous version of hashicorp/null from the dependency lock file
            ╷
            │ Error: Failed to query available provider packages
            │ 
            │ Could not retrieve the list of available versions for provider
            │ hashicorp/null: locked provider registry.terraform.io/hashicorp/null 3.1.0
            │ does not match configured version constraint 3.2.2; must use terraform init
            │ -upgrade to allow selection of new versions
            ╵

caused some test failure, https://github.com/runatlantis/atlantis/actions/runs/9470306781/job/26091248454

this is handled by #4653 along with other fixes