Fix push with template

[lucklove]

What problem does this PR solve?

Introduced by #1044, TiUP can't notice that the TiDBSpec don't have DataDir and will render an empty string

What is changed and how it works?

Convert pointer to struct it point to if the s of renderSpec is a pointer.

Check List

Tests

• Unit test

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[codecov-io]

Codecov Report

Merging #1049 (0170126) into master (65f061d) will decrease coverage by 4.16%.
The diff coverage is 20.00%.

@@            Coverage Diff             @@
##           master    #1049      +/-   ##
==========================================
- Coverage   55.94%   51.78%   -4.17%     
==========================================
  Files         282      282              
  Lines       19860    19868       +8     
==========================================
- Hits        11111    10288     -823     
- Misses       7029     7956     +927     
+ Partials     1720     1624      -96     

Flag	Coverage Δ
cluster	38.35% <0.00%> (-5.67%)	⬇️
dm	23.94% <0.00%> (-0.08%)	⬇️
integrate	46.02% <0.00%> (-4.24%)	⬇️
playground	20.31% <ø> (ø)
tiup	16.48% <ø> (-0.03%)	⬇️
unittest	22.28% <20.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
pkg/cluster/manager/transfer.go	10.66% <20.00%> (-44.56%)	⬇️
components/cluster/command/check.go	6.73% <0.00%> (-72.76%)	⬇️
pkg/cluster/task/limits.go	0.00% <0.00%> (-68.75%)	⬇️
pkg/cluster/task/sysctl.go	0.00% <0.00%> (-66.67%)	⬇️
pkg/cluster/task/copy_file.go	0.00% <0.00%> (-54.55%)	⬇️
components/cluster/command/audit.go	27.27% <0.00%> (-54.55%)	⬇️
pkg/cluster/operation/check.go	0.00% <0.00%> (-53.07%)	⬇️
pkg/cluster/manager/patch.go	0.00% <0.00%> (-51.81%)	⬇️
pkg/cluster/task/rmdir.go	0.00% <0.00%> (-50.00%)	⬇️
pkg/cluster/manager/cleanup.go	0.00% <0.00%> (-49.19%)	⬇️
... and 34 more

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[AstroProfundis]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 4d631a7