change: make task_name mandatory for labels

[surajkota]

Issue #1015

Description of changes:

• Avoid pushing action-id, client-id and parent-action-id for cloudwatch to allow user to plot graphs for period runs
• Make task_name a mandatory dimension in labels and add validation for dimension name and value according to K8s labels syntax. It is a subset of requirements for Cloudwatch dimension
• Add integration tests in transpiler for labels
• Updates to documentation and sample benchmarks

Testing: Used pipeline to run a benchmark job for positive and negative inputs Also used Json validator tools online to verify the changes to the schema

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[jlcontreras]

Left two comments, one of them is a nit, but the other one would be a nice addition, since the system breaks if custom labels don't fill that condition