CI: Split the RISC-V Build Jobs into smaller jobs

To speed up the CI Workflow, this PR splits the CI Build Jobs for RISC-V into smaller jobs. Each job will now complete within 1 hour.

Before the PR: There are 2 jobs for RISC-V, each requiring more than 1.5 hours
- `risc-v-01` (1 hour 42 mins): BL602, Ox64, ESP32-C3 / C6 / H2
- `risc-v-02` (1 hour 41 mins): K230, Icicle, QEMU, RV32M1-Vega

After the PR: The build is spread across 6 jobs for RISC-V, each job completes within 1 hour
- `risc-v-01` (19 mins): BL602, Ox64
- `risc-v-02` (44 mins): ESP32-C3
- `risc-v-03` (45 mins): ESP32-C6, ESP32-H2
- `risc-v-04` (31 mins): K230, Icicle
- `risc-v-05` (41 mins): QEMU CITest
- `risc-v-06` (38 mins): Rest of QEMU, RV32M1-Vega

Following the same convention as the Arm32 Build Jobs, the above jobs are sorted by Target Name. Performance of the RISC-V Build Jobs is discussed in https://github.com/apache/nuttx/issues/13775

tools/ci/testlist/risc-v-06.dat

@@ -0,0 +1,7 @@
+/risc-v/qemu-rv/rv-virt/configs/[d-z]*
+/risc-v/q[f-z]*
+/risc-v/[r-z]*
+
+# Boards build by CMake
+CMake,rv-virt:smp
+CMake,rv-virt:smp64