Move from deprecated Terraform backend locking using dynamodb_table to use_lockfile.

[ibehren1]

Issue #, if available:
n/a

Description of changes:
Terraform 1.11.4 is the current version as of 4/9/2025. In Terraform 1.11.x and greater, using dynamodb_table has been deprecated in favor of use_lockfile. Running the code with 1.11.x+ throws following warning.

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│ Warning: Deprecated Parameter
│
│   on backend.tf line 10, in terraform:
│   10:     dynamodb_table = "daivi-ibehr-tf-back-end-lock"
│
│ The parameter "dynamodb_table" is deprecated. Use parameter "use_lockfile" instead.
|

Included code works for Terraform 1.11.x and should work for 1.10.x. Project should be updated to require Terraform>=1.10.x which supports use_lockfile.

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