fix: normalize json encoded parameters for btp subaccount resources

[ANUGRAHG]

Purpose

• This change introduces normalization of JSON-encoded data using jsontypes.normalized from the Terraform Plugin Framework JSON Types package.
• Replaced types.String with jsontypes.Normalized for the parameters attribute.
• closes [BUG] JSON parameters in btp_subaccount_environment_instance normalization #1211

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[x] Bugfix
[ ] Feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Test the code via automated test

make test

What to Check

Verify that the following are valid:

• Automated tests are executed successfully

Other Information

Checklist for reviewer

The following organizational tasks must be completed before merging this PR:

• The PR status on the Project board is set (typically "in review").
• The PR has the matching labels assigned to it.
• If the PR closes an issue, the issue is referenced.
• Possible follow-up issues are created and linked.

[lechnerc77]

Check necessary:

• Creation of resources via a provider version like 1.17 and then upgrading to this provider -> terraform plan
• Creation of resources via a provider version like 1.17 and then upgrading to this provider, making a change -> terraform plan

-> is there a scheam upgrade necessary

[ANUGRAHG]

Verified both scenarios.

• Created resources using provider version 1.17, then upgraded to the new provider → terraform plan shows no changes.
• Created resources using 1.17, upgraded to the new provider, and made a change → terraform plan reflects only the intended updates. Once applied, the next terraform plan shows no changes.

Everything works as expected.