doubts: re-base spec references to ETSI TS 104-175 / TS 104-176

GS CIM 009 v1.9.1 was split into TS 104 175 (Core API) + TS 104 176 (HTTP
binding). Re-anchor every clause reference in testsuite-doubts.md to the new
numbering, prefixed with its document; tables cited by caption (the new spec
auto-numbers tables).