Bump the default premine balance

[laviniat1996]

Description

This PR bumps the DefaultPremineBalance from 1000 units of native network currency to 1 million units of native network currency.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have updated the official documentation

Testing

• I have tested this code with the official test suite
• I have tested this code manually

Documentation update

(https://github.com/maticnetwork/matic-docs/pull/1086)

[0xAleksaOpacic]

LGTM, congrats on your first contribution 🚀

[codecov]

Codecov Report

Merging #715 (f1d4514) into develop (c39d854) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #715      +/-   ##
===========================================
- Coverage    52.51%   52.49%   -0.02%     
===========================================
  Files          130      130              
  Lines        17069    17069              
===========================================
- Hits          8964     8961       -3     
- Misses        7462     7464       +2     
- Partials       643      644       +1     

Impacted Files	Coverage Δ
network/server_discovery.go	73.88% <0.00%> (-1.92%)	⬇️

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[laviniat1996]

I have read the CLA Document and I hereby sign the CLA

[zivkovicmilos]

Looks good 💯