Fix socket-bound TLS post-handshake authentication progress (#136475)

Fix a post-handshake authentication race that can leave a socket-bound TLS session waiting indefinitely even though the peer has finished the exchange.

The first native handshake call currently invokes SSL_peek, which can process a fast peer’s entire response. The driver then returns NeedMoreData because it considers that call request-flushing only. Subsequent calls wait for socket readability, but the response has already been consumed.

Separate request emission from response processing: skip the peek while flushing the initial certificate request, then retain it on subsequent calls. This preserves write-backpressure retries, handshake completion checks, and certificate-validation suspension. Extend the existing TLS 1.2/1.3 theory with idle-peer cases to verify that sending the request alone does not prematurely complete authentication. No timeout increases or test skips.

Validation

Linux clr+libs baseline and native/managed incremental builds passed with zero warnings or errors. The WSL baseline used explicit Git revision metadata for the Windows-created worktree.
Controlled managed fast-peer reproduction: both TLS 1.2/1.3 cases timed out before the fix and passed afterward. The temporary BIO scheduling hook was removed before final validation.
Full System.Net.Security functional suite: 5,127 passed, 0 failed, 8 existing conditional skips.
Focused four-case theory repeated five times in each reported configuration (DOTNET_JitStress=2 with tiering enabled, and with DOTNET_JitStressRegs=4 and tiering disabled): 40 passed, 0 skipped.
Native schedule/certificate controls: 2,400 cases, zero unexpected outcomes.

Validation used Ubuntu WSL and OpenSSL 3.5.3, not the exact AzureLinux CI image. Older OpenSSL versions and forced write-backpressure were not exercised.

Resolves dotnet/runtime#134222

[!NOTE] This pull request was authored with assistance from GitHub Copilot.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

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