ci: build the KC110 and the Tapo TC70 v3 instead of skipping them (#132)

Both devices have had a complete devices/<dir>/ in this tree for a long time and had
never once been built. #120 froze that state rather than changing it -- it put the 7
defconfigs that were in no master.yml matrix into NOT_BUILT so that a device falling out
of CI would be a test failure instead of a silent skip. Freezing was right for a change
whose job was to not alter what gets built; it was never meant to be permanent for
devices whose only problem is that nobody added the matrix line.

Two contributors did try to add that line. #111 (Tapo TC70 v3, July) and #108 (KC110,
June) both append to the device list in master.yml, which is where the registry lived
when they were written. It does not live there any more -- the matrix is read off the
tree -- so both PRs are merge conflicts now, and the devices they asked for are exactly
the two entries removed here. This is their CI half, landed the way the selector wants
it. #108 also carries a BR2_OPENIPC_MAJESTIC="ultimate" line and a vendor
libsns_ov2735.so for the no-video bug; those are unaffected and stay with that PR.

The two self-test cases that used t31_lite_tp-link-tapo-tc70-v3 as their example of an
unbuilt device move to t31_lite_xiaomi-mjsxj05hl, which is still in NOT_BUILT. The
overlay case also switches to a path that exists, since the device it now names has no
etc/inittab.

Neither device had ever been through a build, so this PR was where we found out. That
was affordable exactly once: a change to ci-matrix.py cannot narrow -- it is what does
the narrowing -- so this ran the full matrix and proved both in the same run. Both are
green:

    Firmware (hi3518ev200_ultimate_tplink-kasa-kc110)   SUCCESS
    Firmware (t31_lite_tp-link-tapo-tc70-v3)            SUCCESS

.github/scripts/ci-matrix.py

@@ -70,7 +70,6 @@ REPO_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__fi
 NOT_BUILT = {
     "gk7102ca_lite_umea-qc01x", "gk7102ca_lite_vstarcam-g8896wip",
     "gk7205v200_rubyfpv_generic", "hi3518ev200_lite_lenovo-snowman-1080p",
-    "hi3518ev200_ultimate_tplink-kasa-kc110", "t31_lite_tp-link-tapo-tc70-v3",
     "t31_lite_xiaomi-mjsxj05hl",
 }
 
@@ -403,15 +402,15 @@ def self_test():
         (["devices/common/br-ext-chip-goke/configs/gk7205v200_fpv_defconfig"],
          1, "a defconfig in a shared directory is still one device"),
         # A defconfig CI does not build contributes nothing.
-        (["devices/t31_lite_tp-link-tapo-tc70-v3/br-ext-chip-ingenic/configs/"
-          "t31_lite_tp-link-tapo-tc70-v3_defconfig"], 0, "an unbuilt device"),
+        (["devices/t31_lite_xiaomi-mjsxj05hl/br-ext-chip-ingenic/configs/"
+          "t31_lite_xiaomi-mjsxj05hl_defconfig"], 0, "an unbuilt device"),
         # ...and so does anything else in that device's directory. Its kernel
         # config is the case that regressed: OpenIPC/builder#126 touched three
         # NOT_BUILT devices and got the full 107 for it.
         (["devices/gk7205v200_rubyfpv_generic/br-ext-chip-goke/board/gk7205v200/"
           "gk7205v200.generic-fpv.config"], 0, "a kernel config in an unbuilt device"),
-        (["devices/t31_lite_tp-link-tapo-tc70-v3/general/overlay/etc/inittab"],
-         0, "an overlay file in an unbuilt device"),
+        (["devices/t31_lite_xiaomi-mjsxj05hl/general/overlay/usr/share/"
+          "openipc/customizer.sh"], 0, "an overlay file in an unbuilt device"),
         # A directory with no defconfig at all is still unknown, and unknown
         # still widens -- that is the half of this rule worth keeping.
         (["devices/a-device-that-does-not-exist/br-ext-chip-goke/board/x.config"],