[FEATURE] - Add the total number of service instances and the number of isolated instances in isolation event.

[chengyouling]

Problem this feature would solve

No response

Describe the solution

No response

Alternatives considered

No response

Additional Context

No response

[liubao68]

Which version do you find this problem and which versions are effected?

[chengyouling]

2.8.x/2.9.x, and please help review the corresponding PR, ths. @liubao68