1.14.6 - Tests timeout on Debian arch riscv64: H5TEST-dsets, H5TEST-set_extent, H5SHELL-test_swmr

**Describe the bug**
The build of HDF5 Debian packages fails on architecture riscv64 due to 3 tests reaching timeout.

Full build log attached.

Log excerpts:
```
test 28
Start 28: H5TEST-dsets

28: Test command: /usr/bin/cmake "-D" "TEST_EMULATOR=" "-D" "TEST_PROGRAM=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin/dsets" "-D" "TEST_ARGS:STRING=" "-D" "TEST_EXPECT=0" "-D" "TEST_SKIP_COMPARE=TRUE" "-D" "TEST_OUTPUT=dsets.txt" "-D" "TEST_LIBRARY_DIRECTORY=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin" "-D" "TEST_FOLDER=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST" "-P" "/home/pini/debian/hdf5-1.14.6+repack/config/cmake/runTest.cmake"
28: Working Directory: /home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST
28: Environment variables:
28: srcdir=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST
28: Test timeout computed to be: 1200
28: -- COMMAND: /home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin/dsets
...
test 47
Start 47: H5TEST-set_extent

47: Test command: /usr/bin/cmake "-D" "TEST_EMULATOR=" "-D" "TEST_PROGRAM=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin/set_extent" "-D" "TEST_ARGS:STRING=" "-D" "TEST_EXPECT=0" "-D" "TEST_SKIP_COMPARE=TRUE" "-D" "TEST_OUTPUT=set_extent.txt" "-D" "TEST_LIBRARY_DIRECTORY=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin" "-D" "TEST_FOLDER=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST" "-P" "/home/pini/debian/hdf5-1.14.6+repack/config/cmake/runTest.cmake"
47: Working Directory: /home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST
47: Environment variables:
47: srcdir=/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST
47: Test timeout computed to be: 1200
47: -- COMMAND: /home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin/set_extent
...
test 105
Start 105: H5SHELL-test_swmr

105: Test command: /usr/bin/bash "/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST/test_swmr.sh"
105: Working Directory: /home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/test/H5TEST
105: Environment variables:
105: LD_LIBRARY_PATH=:/home/pini/debian/hdf5-1.14.6+repack/debian/build-serial/bin
105: Test timeout computed to be: 1200
...
1618/2951 Test #28: H5TEST-dsets ...............................................................***Timeout 1200.13 sec
2311/2951 Test #47: H5TEST-set_extent ..........................................................***Timeout 1200.14 sec
2951/2951 Test #105: H5SHELL-test_swmr ..........................................................***Timeout 1200.07 sec
```

**Expected behavior**
All tests pass.

**Platform (please complete the following information)**
- HDF5 version: 1.14.6
- OS and version: Debian sid on architecture riscv64
- Compiler and version: GCC-15.2.0
- Build system: cmake 3.31.6
- Any configure options you specified:
```
-DHDF5_INSTALL_LIB_DIR=lib/riscv64-linux-gnu -DDEFAULT_API_VERSION=v114 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DHDF5_ENABLE_OPTIMIZATION:BOOL=ON -DBUILD_SHA
RED_LIBS:BOOL=ON -DCMAKE_BUILD_WITH_INSTALL_RPATH:BOOL=OFF -DHDF5_ENABLE_SZIP_SUPPORT:BOOL=ON -DHDF5_ENABLE_Z_LIB_SUPPORT:BOOL=ON -DHDF5_BUILD_FORTRAN:BOOL=ON -DHDF5_BUILD_HL_LIB:BOOL=ON -DHDF5_BUILD_TOOLS:BOOL=
ON -DHDF5_ENABLE_ROS3_VFD:BOOL=ON -DHDF5_BUILD_FLAVOR=serial -DHDF5_INSTALL_INCLUDE_DIR=include/hdf5/serial -DH5_DEFAULT_PLUGINDIR=lib/riscv64-linux-gnu/hdf5/serial/plugins -DALLOW_UNSUPPORTED:BOOL=ON -DHDF5_E
NABLE_THREADSAFE:BOOL=ON -DHDF5_BUILD_CPP_LIB:BOOL=ON -DHDF5_BUILD_JAVA:BOOL=ON -DHDF5_INSTALL_JAR_DIR=lib -DJAVA_AWT_INCLUDE_PATH="NotNeeded" -DCMAKE_JAVA_COMPILE_FLAGS="-source;1.8;-target;1.8"
```
- MPI library: no MPI

**Additional context**
Architecture riscv64 is an official Debian release architecture. Failure to build on this arch is a release critical bug.

[build.log.gz](https://github.com/user-attachments/files/22728138/build.log.gz)