### What changes were proposed in this pull request?
Adding a flag indicating high load in the worker's heartbeat allows the master to better schedule the workers
### Why are the changes needed?
In our production environment, there is a node with abnormally high load, but the master is not aware of this situation. It assigned numerous jobs to this node, and as a result, the stability of these jobs has been affected.
### Does this PR introduce _any_ user-facing change?
NO
### How was this patch tested?
UT
Closes#1840 from JQ-Cao/920.
Lead-authored-by: Keyong Zhou <zky.zhoukeyong@alibaba-inc.com>
Co-authored-by: caojiaqing <caojiaqing@bilibili.com>
Signed-off-by: zky.zhoukeyong <zky.zhoukeyong@alibaba-inc.com>
1d04a23289