* fleet support elastic train

* fleet support elastic train

* support elastic

* add unittest

* fix unitest bug

* fix unittest bug

* fix unittest bug

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix elastic bug

* fix ci fail

* fix ci fail

* fix elastic bug

* fix elastic bug

* fix joint debugging bug

* fix joint debugging bug

* fix windows ci failed

* fix windows ci failed

* Optimize fleet elastic scale in/out

* elastic support pre hook

* add prehook unittest