docs: set example default values as integers from byte strings

[ahinsutime]

What this PR does / why we need it:
This pull request set consistent example integer values for ingester and block_builder that were in string type before.

at ingester

ingester:
  ...
  [chunk_target_size: <int> | default = 1572864]
  ...

at block_builder

block_builder:
  ...
  [chunk_target_size: <int> | default = 1536KB]
  ...

Which issue(s) this PR fixes:
Fixes #19035

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.