azurerm_web_application_firewall_policy - update tests using managed_rules.managed_rule_set.version 3.1 -> 3.2

[mbfrahry]

This PR fixes tests using managed_rules.managed_rule_set.version 3.1 which does not support request_body_inspect_limit_in_kb causing issues like

              ~ policy_settings {
                  ~ request_body_inspect_limit_in_kb = 0 -> 128
                    # (5 unchanged attributes hidden)
                }

This PR updates all tests using 3.1 to 3.2

[catriona-m]

LGTM!

[github-actions]

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