list_revoked_tokens sql speedup for havana

This consists of the following 3 patches:

    Narrow columns used in list_revoked_tokens sql

    Currently the SQL backend lists revoked tokens by selecting all of the
    columns, including the massive "extra" column. This places a significant
    burden on the client library and wastes resources. We only need the
    id/expired columns to satisfy the API call.

    In tests this query was several orders of magnitude faster with just two
    thousand un-expired revoked tokens.
    (cherry picked from commit ab7221246af394f24e47484e822b8dcda37411aa)

    Add index to cover revoked token list

    The individual expires and valid indexes do not fully cover the most
    common query, which is the one that lists revoked tokens.

    Because valid is only ever used in conjunction with expires, we do not
    need it to have its own index now that there is a covering compound
    index for expires and valid.

    Note that he expires index is still useful alone for purging old tokens
    as we do not filter for valid in that case.
    (cherry picked from commit dd2c80c566f20a97a22e0d7d5a514be84772a955)

    Remove unused token.valid index

    Because valid is only ever used in conjunction with expires, we do not
    need it to have its own index now that there is a covering compound
    index for expires and valid.

    Note that he expires index is still useful alone for purging old tokens
    as we do not filter for valid in that case.
    (cherry picked from commit 5d8a1a41420aa20d2aa21da6311c9d55b9e373b6)

Change-Id: I04d62b98d5d760a3fbc3c8db61530f7ebccb0a48
Closes-Bug: #1253755
Merge "list_revoked_tokens sql speedup for havana" into stable/havana