*: update the import path(release-3.0)

[nolouch]

Signed-off-by: nolouch nolouch@gmail.com

What problem does this PR solve?

ref: #2758

• update import path
• cancel go mod v3

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test

Release note

• change import path from pingcap/pd to tikv/pd

[nolouch]

/run-all-tests

[codecov]

Codecov Report

Merging #2779 into release-3.0 will increase coverage by 0.04%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           release-3.0    #2779      +/-   ##
===============================================
+ Coverage        69.72%   69.77%   +0.04%     
===============================================
  Files              171      171              
  Lines            16987    16987              
===============================================
+ Hits             11845    11853       +8     
+ Misses            4162     4153       -9     
- Partials           980      981       +1     

Impacted Files	Coverage Δ
client/client.go	71.81% <ø> (ø)
pkg/metricutil/metricutil.go	94.44% <ø> (+8.33%)	⬆️
pkg/mock/mockclassifier/mockclassifier.go	30.00% <ø> (ø)
pkg/mock/mockcluster/mockcluster.go	90.68% <ø> (ø)
pkg/mock/mockhbstream/mockhbstream.go	85.71% <ø> (ø)
pkg/mock/mockoption/mockoption.go	92.77% <ø> (ø)
pkg/testutil/operator_check.go	83.33% <ø> (ø)
server/api/admin.go	64.70% <ø> (ø)
server/api/classifier.go	66.66% <ø> (ø)
server/api/cluster.go	75.00% <ø> (ø)
... and 103 more

---

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[HunDunDM]

LGTM

[JmPotato]

LGTM

[ti-srebot]

@JmPotato,Thanks for your review. However, LGTM is restricted to Reviewers or higher roles.See the corresponding SIG page for more information. Related SIGs: scheduling(slack).

[nolouch]

/merge

[ti-srebot]

/run-all-tests