Update template variable schemas with type field in dashboards and shared dashboards endpoints for group by template variables

[api-clients-generation-pipeline]

See DataDog/datadog-api-spec#4011
Test branch datadog-api-spec/test/heather/tvar-type

[datadog-datadog-prod-us1]

Datadog Report

Branch report: datadog-api-spec/generated/4011
Commit report: 0dd6d1a
Test service: org.codehaus.plexus.classworlds.launcher.launcher

❌ 12 Failed (0 Known Flaky), 5068 Passed, 144 Skipped, 4m 22.49s Total Time

❌ Failed Tests (12)

This report shows up to 5 failed tests.

• Create a new dashboard with template variable type field returns "OK" response - classpath:com/datadog/api/client/v1/api/dashboards.feature:Dashboards - Details

  Expand for error

   Cannot invoke "java.time.OffsetDateTime.toEpochSecond()" because "this.now" is null
  

• Create a new dashboard with template variable type field returns "OK" response - classpath:com/datadog/api/client/v1/api/dashboards.feature:Dashboards

• Create a new dashboard with template variable type field returns "OK" response - classpath:com/datadog/api/client/v1/api/dashboards.feature:Dashboards

• Create a new dashboard with template variable type field returns "OK" response - classpath:com/datadog/api/client/v1/api/dashboards.feature:Dashboards

• Create a shared dashboard with a group template variable returns "OK" response - classpath:com/datadog/api/client/v1/api/dashboards.feature:Dashboards