[esp32] Respect user sdkconfig values in the TLS trims, keep EC key parsing

Review follow-ups: the FINAL reconcile job now uses the set-if-absent
helper so explicit sdkconfig_options win, and skips the whole TLS role
choice when the user set any of its members. The EC public-key parsing
options stay enabled because they decide whether a peer certificate with a
compressed point or explicit curve parameters parses. Adds an ESP32-C6
http_request compile test so CI links the vasprintf wrap, and suppresses
clang-tidy's no-malloc check on the allocation that vasprintf's contract
requires.

tests/components/http_request/test.esp32-c6-idf.yaml

@@ -0,0 +1,4 @@
+substitutions:
+  verify_ssl: "true"
+
+<<: !include common.yaml