[lldb] Fix PipeTest name collision in unit tests

We had two classes named `PipeTest`: one in `PipeTestUtilities.h` and
one in `PipeTest.cpp`. The latter was unintentionally using the wrong
class (from the header) which didn't initialize the HostInfo subsystem.

This resulted in a crash due to a nullptr dereference (`g_fields`) when
`PipePosix::CreateWithUniqueName` called `HostInfoBase::GetProcessTempDir`.

(cherry picked from commit e89458d)

Author: JDevlieghere

lldb/unittests/DAP/TestBase.cpp

@@ -29,7 +29,7 @@ using lldb_private::NativeFile;
 using lldb_private::Pipe;
 
 void TransportBase::SetUp() {
-  PipeTest::SetUp();
+  PipePairTest::SetUp();
   to_dap = std::make_unique<Transport>(
       "to_dap", nullptr,
       std::make_shared<NativeFile>(input.GetReadFileDescriptor(),

lldb/unittests/Host/JSONTransportTest.cpp

@@ -14,12 +14,12 @@ using namespace llvm;
 using namespace lldb_private;
 
 namespace {
-template <typename T> class JSONTransportTest : public PipeTest {
+template <typename T> class JSONTransportTest : public PipePairTest {
 protected:
   std::unique_ptr<JSONTransport> transport;
 
   void SetUp() override {
-    PipeTest::SetUp();
+    PipePairTest::SetUp();
     transport = std::make_unique<T>(
         std::make_shared<NativeFile>(input.GetReadFileDescriptor(),
                                      File::eOpenOptionReadOnly,

lldb/unittests/TestingSupport/Host/PipeTestUtilities.h

@@ -14,7 +14,7 @@
 #include "gtest/gtest.h"
 
 /// A base class for tests that need a pair of pipes for communication.
-class PipeTest : public testing::Test {
+class PipePairTest : public testing::Test {
 protected:
   lldb_private::Pipe input;
   lldb_private::Pipe output;