Add etcd max snapshot and wals

[liupeng0518]

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/kind api-change
/kind bug
/kind cleanup
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/kind failing-test
/kind feature
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/kind feature

What this PR does / why we need it:
Add etcd flags: snapshot and wals

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: floryut, liupeng0518

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[oomichi]

confirmed the environment variable names and the default values according to https://etcd.io/docs/v2/configuration/

–max-snapshots

    Maximum number of snapshot files to retain (0 is unlimited)
    default: 5
    env variable: ETCD_MAX_SNAPSHOTS
    The default for users on Windows is unlimited, and manual purging down to 5 (or your preference for safety) is recommended.

–max-wals

    Maximum number of wal files to retain (0 is unlimited)
    default: 5
    env variable: ETCD_MAX_WALS
    The default for users on Windows is unlimited, and manual purging down to 5 (or your preference for safety) is recommended.

/ok-to-test
/lgtm