Allow governance upgrades to change the TrustingPeriod of an IBC client

[charleenfei]

Summary

currently, changing the trusting period will cause a governance upgrade of a client to fail as we assume that the security properties should remain the same across client upgrades. however, there are situations where a trusting period has been incorrectly misconfigured for a canonical channel, governance should be allowed to upgrade this parameter (see: EVMOS)

Problem Definition

Proposal

Null trusting period in IsMatchingClientState

Set new trusting period

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