Fix warnings

[dblock]

Is your feature request related to a problem? Please describe.

Some of these warnings are probably low hanging fruit.

> Task :compileKotlin
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/ManagedIndexCoordinator.kt: (392, 25): Variable 'response' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/model/ManagedIndexConfig.kt: (181, 35): Elvis operator (?:) always returns the left operand of non-nullable type String?
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/model/coordinator/SweptManagedIndexConfig.kt: (37, 40): Parameter 'id' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/step/rollup/AttemptCreateRollupJobStep.kt: (101, 17): Variable 'response' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/transport/action/explain/ExplainAllResponse.kt: (40, 38): Unchecked cast: (Mutable)Map<String!, Any!>? to Map<String, Boolean>
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/transport/action/explain/TransportExplainAction.kt: (159, 78): Unchecked cast: Any? to Map<String, Any>
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/indexstatemanagement/util/ManagedIndexUtils.kt: (583, 64): Unchecked cast: Any? to Map<String, Any>?
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/action/index/TransportIndexRollupAction.kt: (140, 24): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/action/index/TransportIndexRollupAction.kt: (140, 43): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/Rollup.kt: (197, 30): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/metric/Average.kt: (17, 17): Parameter 'sin' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/metric/Max.kt: (17, 17): Parameter 'sin' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/metric/Min.kt: (17, 17): Parameter 'sin' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/metric/Sum.kt: (17, 17): Parameter 'sin' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/rollup/model/metric/ValueCount.kt: (17, 17): Parameter 'sin' is never used
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/transform/action/get/TransportGetTransformsAction.kt: (82, 26): Unchecked cast: ActionListener<GetTransformsResponse> to ActionListener<ActionResponse>
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/transform/action/index/TransportIndexTransformAction.kt: (149, 27): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/transform/action/index/TransportIndexTransformAction.kt: (149, 49): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/transform/model/Transform.kt: (136, 30): 'roles: List<String>' is deprecated. Will be ignored, to check the roles use user field
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/util/ScheduledJobUtils.kt: (76, 55): Unchecked cast: List<Any> to List<Rollup>
w: /tmp/tmp5yzztbrc/index-management/src/main/kotlin/org/opensearch/indexmanagement/util/ScheduledJobUtils.kt: (77, 64): Unchecked cast: List<Any> to List<Transform>

Describe the solution you'd like
Fix warnings and turn on warnings as errors in the build.

[bowenlan-amzn]

Close as we have cleaned up all the compile warnings and force future commits to fix warnings before merging in.