add ddb ttl resource-exceptions for inexistent tables

[ackdav]

Motivation

This PR addresses that the DDB operations DescribeTimeToLive and UpdateTimeToLive both had no checks in regards to the existence of the table, as highlighted in #9030.

The ResourceNotFoundException message might look peculiar, but this is due to parity:

$ aws dynamodb describe-time-to-live --table-name test

An error occurred (ResourceNotFoundException) when calling the DescribeTimeToLive operation: Requested resource not found: Table: test not found

$ aws dynamodb update-time-to-live --table-name test --time-to-live-specification Enabled=true,AttributeName=ttl

An error occurred (ResourceNotFoundException) when calling the UpdateTimeToLive operation: Requested resource not found: Table: test not found

I would've liked to prove this via a snapshot test, but the refactoring was out of scope for this simple patch.

fixes: #9030

Changes

• add resource checks for both operations
• add a simple check to the test

[coveralls]

coverage: 80.439% (-0.01%) from 80.451% when pulling a6a6362 on fix_ddb_ttl_default into 5217b87 on master.

[github-actions]

LocalStack Community integration with Pro

       2 files         2 suites   1h 25m 45s ⏱️
2 151 tests 1 677 ✔️ 474 💤 0 ❌
2 152 runs  1 677 ✔️ 475 💤 0 ❌

Results for commit a6a6362.