Set RCD for 100% drop_overload case as unconditional_drop_overload

[yanjunxiang-google]

This is a follow up commit of drop_overload support:#30827.

It is observed that in some situations, EDS sends drop_overload ratio as 100% for some clusters do not have healthy endpoints in the cluster. For such cases, it is preferred that the RCD of the local reply set to "unconditional drop overload" to make it a little bit different from the normal "drop overload" case.

[repokitteh-read-only]

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🐱

Caused by: #38408 was opened by yanjunxiang-google.

see: more, trace.

[yanjunxiang-google]

envoy/test/integration/eds_integration_test.cc

Line 803 in cedb633

TEST_P(EdsIntegrationTest, DropOverloadTestForEdsClusterAllDrop) { dropOverloadTest(100, "503"); }

tested drop_overload = 100% case.

[yanjunxiang-google]

/assign @yanavlasov @yurykats