[Fix] Add missing H2 header in `mws_network_connectivity_configs.md` and optimization in `data_mws_network_connectivity_configs`

[840]

Changes

• Add missing H2 header in mws_network_connectivity_configs.md
• Remove unnecessary variable in data_mws_network_connectivity_configs

Tests

Ran integration test

• [x] make test run locally
• [x] relevant change in docs/ folder
• [x] covered with integration tests in internal/acceptance
• [x] relevant acceptance tests are passing
• [x] using Go SDK

[github-actions[bot]]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger: go/deco-tests-run/terraform

Inputs:

• PR number: 4256
• Commit SHA: 6f22aa4cf92621960949e70def808e4dcd5266fa

Checks will be approved automatically on success.

[eng-dev-ecosystem-bot]

Test Details: go/deco-tests/11949347015