[Backport release-1.4] Fix: address vela-core crash due to empty policy properties (#4473)

[Somefive]

• Fix: fix topology core crash

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

• Test: add tests

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

• Fix: same problem in other places

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

• Style: remove empty line

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

• Feat: raise error when empty topology is used

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

• Feat: raise error when empty override policy is used

Signed-off-by: Charlie Chiang charlie_c_0129@outlook.com

Description of your changes

Fixes #

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Special notes for your reviewer

[codecov]

Codecov Report

Merging #4480 (fc14121) into release-1.4 (4cb9a14) will decrease coverage by 11.43%.
The diff coverage is 87.50%.

@@               Coverage Diff                @@
##           release-1.4    #4480       +/-   ##
================================================
- Coverage        58.47%   47.03%   -11.44%     
================================================
  Files              331      296       -35     
  Lines            31975    27788     -4187     
================================================
- Hits             18697    13070     -5627     
- Misses           10776    13209     +2433     
+ Partials          2502     1509      -993     

Flag	Coverage Δ
apiserver-unittests	?
core-unittests	54.84% <87.50%> (+0.19%)	⬆️
e2e-multicluster-test	20.17% <0.00%> (+0.05%)	⬆️
e2e-rollout-tests	22.42% <0.00%> (-0.02%)	⬇️
e2etests	29.52% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/policy/envbinding/utils.go	64.70% <0.00%> (ø)
pkg/policy/override.go	100.00% <100.00%> (ø)
pkg/policy/topology.go	95.34% <100.00%> (+0.22%)	⬆️
pkg/resourcekeeper/gc.go	77.35% <100.00%> (+0.94%)	⬆️
pkg/workflow/providers/multicluster/deploy.go	80.21% <100.00%> (+2.69%)	⬆️
pkg/apiserver/utils/version.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/apiserver/utils/cache.go	0.00% <0.00%> (-92.60%)	⬇️
pkg/apiserver/domain/service/service.go	0.00% <0.00%> (-92.31%)	⬇️
pkg/apiserver/domain/model/workflow.go	11.76% <0.00%> (-88.24%)	⬇️
pkg/apiserver/utils/http.go	0.00% <0.00%> (-87.50%)	⬇️
... and 142 more

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