Remove transaction when listing projects

[davidheryanto]

What this PR does / why we need it:
Listing projects is a read only operation and therefore should not need the @Transactional Hibernate annotation.

Having @Transactional annotation results in excessive locks being used when listing projects because of the INSERT and DELETE queries generated. As a result, when other operations such as job updates (which is also Transactional) is running, users trying to list projects will often encounter GRPC error TimeoutExceeded because ListProjects will wait a long for the shared lock to be available.

When there is at least one feature set registered, these are the generated queries when listing projects:

sql.with.transaction.log
sql.no.transaction.log

Without @Transaction no INSERT and DELETE queries are generated and hence it will not wait for lock to be available when listing projects.

The generated queries can be logged with this log4j2 configuration in feast-core:

<Logger name="org.hibernate.SQL" level="debug" additivity="false">
      <AppenderRef ref="ConsoleAppender"/>
</Logger>

Which issue(s) this PR fixes:

NONE

Does this PR introduce a user-facing change?:

NONE

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This pull-request has been approved by: davidheryanto

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[zhilingc]

IMO none of these methods need to be transactional, but
/lgtm