chore: avoid duplicate coverage data upload

[JLHwung]

Q	A
Fixed Issues?	Avoid calling codecov API twice, reduce carbon footprint 😄
License	MIT

Recently I noticed that the coverage data of @babel/traverse is incorrect: https://codecov.io/gh/babel/babel/src/eec01fe078decb7d369cd2111c9f3881c4482788/packages/babel-traverse/src/path/index.js

i.e. The NodePath is a very popular. It is unlikely that NodePath had been executed only twice in the test suites. In fact I have checked out my local coverage report, the NodePath has been executed for a million times:

I checked out test process and realized that we uploaded coverage twice. I removed the one in Makefile and see the coverage on codecov.io is back to normal.

I will mark as ready when this issue is resolved.

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[JLHwung]

Alright, it seems that the green number on codecov.io is how many builds (in our cases, only 1 build uploads coverage report) each line is covered in.

https://codecov.io/gh/babel/babel/src/744f239283337c1e3091a7905a0c057ed4877a94/packages/babel-traverse/src/path/index.js

When you hover on the green number 1, it will print the hit number (e.g. "> 10k"). Not particularly for my own purpose (finding the hottest path of @babel/traverse) but good to know about that.

That means #11968 should work, I will see if I can revive that PR.