fix(alert detected type): don't default to leaked secret

[lxmcgvrn]

• fixes a minor nit in getIssueDetectedType where we were defaulting to "leaked" secret if an alert was not malicious
• fixes a failing test in AlertsTable caused by isColumnHeader being applied to the time, rather than the "type" of alert

[coveralls]

Pull Request Test Coverage Report for Build 12990646744

Details

• 6 of 7(85.71%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 68.305%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/lib/utils.ts	2	3	66.67%

Totals
Change from base Build 12988609897:	0.07%
Covered Lines:	768
Relevant Lines:	1023

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💛 - Coveralls