[testbug] Adapt nsk tests to the RISC-V platform

Since riscv does not have a shared memory connector,
the following test fails on linux-riscv64 with the jtreg patch
of https://bugs.openjdk.java.net/browse/CODETOOLS-7903138:

- vmTestbase/nsk/jdb/options/connect/connect003/connect003.java
- vmTestbase/nsk/jdb/options/connect/connect005/connect005.java
- vmTestbase/nsk/jdb/options/listconnectors/listconnectors001/listconnectors001.java
- vmTestbase/nsk/jdi/AttachingConnector/attach/attach002/TestDescription.java
- vmTestbase/nsk/jdi/AttachingConnector/attach/attach005/TestDescription.java
- vmTestbase/nsk/jdi/AttachingConnector/attachnosuspend/attachnosuspend003/TestDescription.java
- vmTestbase/nsk/jdi/LaunchingConnector/launch/launch002/TestDescription.java
- vmTestbase/nsk/jdi/LaunchingConnector/launch/launch004/TestDescription.java
- vmTestbase/nsk/jdi/ListeningConnector/accept/accept002/TestDescription.java

Failed log example:
```
launcher > Starting local debuggee.
launcher > Start jdb attaching to local debuggee
Creating file for jdb stdout stream: ./jdb.stdout
Creating file for jdb session: ./jdb.session
Creating file for jdb stderr stream: ./jdb.stderr
debuggee.stderr> ERROR: transport library not found: dt_shmem
debuggee.stderr> ERROR: JDWP Transport dt_shmem failed to initialize, TRANSPORT_LOAD(509)
debuggee.stderr> JDWP exit error AGENT_ERROR_TRANSPORT_LOAD(196): No transports initialized [/home/jiangfeilong/workspace/jdk/src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c:734]
debuggee.stdout> FATAL ERROR in native method: JDWP No transports initialized, jvmtiError=AGENT_ERROR_TRANSPORT_LOAD(196)
```
test will try to launch attached jdb repetitively until timeout.