hostmetricsreceiver: (network/paging/process) Refactor to use metrics metadata

[asuresh4]

Depends on #2406

Refactor network, paging, process and processes scrapers to use metrics metadata utility.

[codecov]

Codecov Report

Merging #2421 (69d7a95) into main (c5f2b25) will decrease coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2421      +/-   ##
==========================================
- Coverage   91.88%   91.80%   -0.08%     
==========================================
  Files         268      264       -4     
  Lines       15213    15073     -140     
==========================================
- Hits        13978    13838     -140     
  Misses        857      857              
  Partials      378      378              

Impacted Files	Coverage Δ
...internal/scraper/networkscraper/network_scraper.go	97.91% <100.00%> (ø)
...nal/scraper/pagingscraper/paging_scraper_others.go	100.00% <100.00%> (ø)
...craper/processesscraper/processes_scraper_linux.go	100.00% <100.00%> (ø)
...scraper/processesscraper/processes_scraper_unix.go	100.00% <100.00%> (ø)
...internal/scraper/processscraper/process_scraper.go	98.13% <100.00%> (ø)
...al/scraper/processscraper/process_scraper_linux.go	100.00% <100.00%> (ø)

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[jrcamp]

Ideally only tests would use New()

[tigrannajaryan]

LGTM. Refactored while keeping current emitted metrics.