Colocate table stays unstable when a large number of be restarts frequently

[gengjun-git]

Describe the bug
When colocate table balance, if multiple be down, the tablets will be distributed to the existing machines, but if the existing machine disk is not enough to accommodate these tablets, and the balance must wait for the migration of these tablets to complete, The strategy will fall into an endless loop.

[gengjun-git]

fix in #4936