runtime/coverage: fix snapshot total calculation

[AlexanderYastrebov]

Sum number of counters to obtain total number of coverable units
instead of using length of the section data.

Updates #62212

[gopherbot]

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[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

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[gopherbot]

Message from Alexander Yastrebov:

Patch Set 1:

(1 comment)

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[gopherbot]

This PR (HEAD: 0151db7) has been imported to Gerrit for code review.

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[gopherbot]

Message from Than McIntosh:

Patch Set 2: Code-Review+2 Run-TryBot+1

(1 comment)

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[gopherbot]

Message from Gopher Robot:

Patch Set 2:

(1 comment)

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[gopherbot]

Message from Gopher Robot:

Patch Set 2: TryBot-Result+1

(1 comment)

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Message from Alexander Yastrebov:

Patch Set 2:

(1 comment)

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Message from Than McIntosh:

Patch Set 2:

(1 comment)

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Message from Alexander Yastrebov:

Patch Set 2:

(1 comment)

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[gopherbot]

Message from Than McIntosh:

Patch Set 2: -Code-Review Hold+1

(1 comment)

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[AlexanderYastrebov]

See CL discussion