fix(engine): reject duration values that wrap time.Duration - #32841

What this PR does / why we need it:

asDuration wraps to MinInt64 instead of returning an error at the upper
float boundary:

{{ durationSeconds 9223372036.854776 }}  -> -9.223372036854776e+09
{{ mustToDuration 9223372036.854776 }}   -> -2562047h47m16.854775808s

float64(math.MaxInt64) rounds up to 2^63, so for
seconds == maxDurationSecondsFloat the computed nanos equals 2^63, passes
the > check, and time.Duration(nanos) wraps to MinInt64. Both helpers go
through asDuration.

Use >= for the upper bound. The lower bound stays < because -2^63 is
representable and is a valid duration. Added boundary cases to
TestDurationHelpers.

Special notes for your reviewer:

Found this while reading the overflow guard added in #31695. The new cases only
pin down the boundary; values below it are unchanged.

If applicable:

• this PR contains user facing changes (the docs needed label should be applied if so)
• this PR contains unit tests
• this PR has been tested for backwards compatibility