[202205] Input check for timeout in generate_dump (#2925)

[maipbui]

Cherry-pick #2925 ADO 28548370

What I did

Added input check for argument "-t" in generate_dump script

How I did it

Made sure only integer values can be received for this argument

How to verify it

Call generate_dump -t with non-integer values

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[maipbui]

/azpw run Azure.sonic-utilities

[mssonicbld]

/AzurePipelines run Azure.sonic-utilities

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).