Remove --impersonate_service_account whenever PipelineOptions are serialized

[tvalentyn]

fixes: #32030 - see the issue description for context.

Some IOs capture pipeline options and inadvertently pass them to Dataflow runner:

https://github.com/apache/beam/blob/release-2.56.0/sdks/python/apache_beam/io/gcp/bigquery.py#L723
https://github.com/apache/beam/blob/release-2.56.0/sdks/python/apache_beam/io/gcp/bigquery.py#L1148

Given that more IOs might do this in the future, this PR adds a custom serialization logic to filter out the impersonate_service_account option whenever we serialize pipeline options, similarly to how we filter it out whenever we convert pipeline options into a proto:

beam/sdks/python/apache_beam/runners/dataflow/internal/apiclient.py

Line 281 in e7847c9

options_dict.pop('impersonate_service_account', None)

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[tvalentyn]

R; @stephenmw

[stephenmw]

LGTM

Thanks!