fix yscale on double histogram notebook chart

[jamie256]

Fixes #479 - issue is that the yscale only considered one of the profiles max values when scaling the y axis, which could truncate the bars in one of the profiles.

Also some incidental minor fixes:
Remove placeholder tooltip text, consistently use "target" instead of "current" terminology when comparing profiles.

General Checklist

• Tests added for this feature/bug
  if it was a bug, test must cover it.
• Conform by the style guides, by using formatter
• Documentation updated
• (optional) Please add a label to your PR

[FelipeAdachi]

LGTM!

[coveralls]

Pull Request Test Coverage Report for Build 2029666146

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.58%

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Totals
Change from base Build 2025072305:	0.0%
Covered Lines:	4935
Relevant Lines:	5811

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💛 - Coveralls