Stop testing with Node <v10; upgrade tchannel->4.x

[yurishkuro]

Which problem is this PR solving?

• the CI no longer succeeds with Node 4
• v10 is EOL in a few days

Short description of the changes

• upgrade tchannel to 4.x to remove dependency on Node 0.10 (YAY!)
• remove all Node versions earlier than v10; add versions 12, 14, 16
• make Node v14 the primary
• use official node/14-alpine base image for crossdock instead of hacky jaegertracing/xdock-node:docker-node-babel which has no source (see Replace docker-node-babel image that disappeared from Docker Hub #439)
  • turns out doing npm install is not that slow in Docker
• clean-up GH actions and Make targets which had many unnecessary installs/uninstalls

[codecov]

Codecov Report

Merging #463 (f912800) into master (4c739a2) will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #463      +/-   ##
==========================================
+ Coverage   98.67%   98.72%   +0.04%     
==========================================
  Files          50       50              
  Lines        2035     2035              
  Branches      383      383              
==========================================
+ Hits         2008     2009       +1     
+ Misses         27       26       -1     

Impacted Files	Coverage Δ
src/reporters/remote_reporter.js	95.74% <0.00%> (+2.12%)	⬆️

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