[aleksandr-miheichev]

Stop adding echForceQuery: "full" to generated TLS settings and remove the obsolete property from TlsSettings4Ray. Preserve echConfigList unchanged, including literal Base64, DNS URLs and the explicit query-domain form.

This retires the legacy-core workaround retained by 2dust/v2rayN#9214. Xray removed runtime handling in XTLS/Xray-core#6032, then removed the deprecated JSON/protobuf fields in XTLS/Xray-core#6226. Stock v26.10.29 ignores this field and enforces ECH when configured. Compatibility with older cores that still depend on the explicit override is outside the verified scope.

Add six generated-JSON regression cases covering Base64, DoH and UDP URLs, an explicit DNS query domain, and null/empty ECH settings. Before the fix, the four populated-ECH cases fail because the legacy field is emitted; after the fix all six pass with SNI and ECH values preserved.

Validation:

• GitHub Actions for d9ede87: Code Test and WebAPI build/runtime verification pass. Linux x64, Windows x64 and Windows ARM64 each execute ServiceLib.Tests 142/142 and WebAPI tests 387/387; native/container builds and runtime smoke checks also pass.
• Windows 11, .NET SDK 10.0.403 / runtime 10.0.14: ServiceLib.Tests 142/142; WebAPI tests 387/387.
• Ubuntu WSL2, .NET SDK 10.0.401 / runtime 10.0.12: ServiceLib.Tests 142/142. WebAPI tests 384/387; the pristine base also gives 384/387. Both runs fail the same two process-tracker tests; each also encounters a connection reset in a different rate-limit test case. The rate-limit class passes 5/5 in an isolated serial rerun.
• Official Xray v26.10.29 Windows/Linux binaries, release hashes verified: 22/22 loopback runtime checks per OS. Real HTTP forwarding over VLESS/TLS/ECH works with native TLS and Chrome/uTLS with the field absent or set to full. Literal Base64 causes no query to the local ECH DNS responder; a UDP DNS URL causes HTTPS RR type 65 queries. Malformed Base64, empty ECH DNS answers and mismatched server keys reject forwarding. An object-valued echForceQuery is also ignored.
• Not run: macOS checks (no available macOS host), DoH runtime interoperability (the controlled DNS fixture uses UDP), external proxy servers and alternate cores.