fix: differentiate dry run action based on live state is nil or not

[howieyuen]

kusion will try ServerSideDryRun first, and fall back to ClientSideDryRun if runtime is not supported.

But, forget to distinguish live state is nil or not, so jsonpatch.MergePatch() return a nil pointer.

[coveralls]

Pull Request Test Coverage Report for Build 3619910019

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 72.407%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	75.0%

Totals
Change from base Build 3589366913:	-0.02%
Covered Lines:	4566
Relevant Lines:	6306

---

💛 - Coveralls

[SparkYuan]

lgtm