Change build task to assemble task

[adityaj1107]

Description

This PR aims at resolving the build issues faced by the infra team. Currently, we have issues (opensearch-project/job-scheduler#56) on job scheduler where the tests are flakey and are failing intermittently. But the open search build uses the task "assemble" to build the artifacts and not run additional checks for all other components which are packaged in the build. This PR makes the job scheduler component also run the assemble task and not the build task.

Issues Resolved

Check List

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[dblock]

This is unlike other components in OpenSearch, isn’t it? Should this be aligned in job-scheduler instead?

[dbbaughe]

@dblock Majority are just assembling artifacts..

https://github.com/opensearch-project/opensearch-build/blob/main/bundle-workflow/scripts/components/notifications/build.sh#L66
https://github.com/opensearch-project/opensearch-build/blob/main/bundle-workflow/scripts/components/security/build.sh#L73
https://github.com/opensearch-project/opensearch-build/blob/main/bundle-workflow/scripts/components/k-NN/build.sh#L83
https://github.com/opensearch-project/opensearch-build/blob/main/bundle-workflow/scripts/components/alerting/build.sh#L63
https://github.com/opensearch-project/opensearch-build/blob/main/bundle-workflow/scripts/components/OpenSearch/build.sh#L100