Lower the ConnMgr.HighWater and LowWater limits

[bbondy]

Resolves brave/brave-browser#13525

Submitter Checklist:

• There is a ticket for my issue.
• Used Github auto-closing keywords in the commit message.
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed).
• Requested a security/privacy review as needed.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

• Fresh profile...
• Open the profile directory
• Open brave_ipfs/config
  The values should be updated for the section Swarm.ConnMgr for LowWater and HighWater

The default is ConnMgr.LowWater=600 and HighWater=900

It should now be changed to:

LowWater=50 and HighWater=300

[bbondy]

macOS had a build failure but it works locally so it's not related.

[LaurenWags]

Verified using

Brave | 1.21.1 Chromium: 88.0.4324.79 (Official Build) nightly (x86_64)
-- | --
Revision | bd1e9353659b2491dac971226a973ca3b5684a14-refs/branch-heads/4324@{#1520}
OS | macOS Version 10.15.7 (Build 19H15)

Verified test plan from #7577 (comment)

Using a clean profile, visited ipfs://QmbWqxBEKC3P8tqsKc98xmWNzrzDtRLMiMPL8wBuTGsMnR to trigger IPFS infobar.
Installed IPFS from infobar.
Opened ~/Library/Application Support/BraveSoftware/Brave-Browser-Nightly/brave_ipfs/config file.

Confirmed updated config values of LowWater=50 and HighWater=300.

Spot checked able to load ipfs:// and ipns:// URLs without issue.