test_runner: exclude ignored branches from BRDA in lcov output

When using node:coverage ignore comments, line coverage (DA entries)
is correctly excluded from the lcov output, but branch coverage (BRDA
entries) for branches pointing to ignored lines still appears as
uncovered. This causes branch coverage percentages to be incorrectly
low.

Skip branches entirely when all their lines are ignored by coverage
comments, consistent with how ignored lines are already excluded from
line reports.

Fixes: #61586

Author: kszongic

lib/internal/test_runner/coverage.js

@@ -193,14 +193,20 @@ class TestCoverage {
           ObjectAssign(range, mapRangeToLines(range, lines));
 
           if (isBlockCoverage) {
+            // Skip branches where all lines are ignored by coverage
+            // comments. This is consistent with how ignored lines are
+            // excluded from line reports (DA entries in lcov).
+            if (range.ignoredLines === range.lines.length) {
+              continue;
+            }
+
             ArrayPrototypePush(branchReports, {
               __proto__: null,
               line: range.lines[0]?.line,
               count: range.count,
             });
 
-            if (range.count !== 0 ||
-                range.ignoredLines === range.lines.length) {
+            if (range.count !== 0) {
               branchesCovered++;
             }