tst_qquickpixmapcache: webOS always tries to load from cache

Start testing of tst_qquickpixmapcache *********
Config: Using QtTest library 6.3.0, Qt 6.3.0 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 9.3.0), webos 2.15.0.g
PASS : tst_qquickpixmapcache::initTestCase()
PASS : tst_qquickpixmapcache::single(local)
PASS : tst_qquickpixmapcache::single(local)
PASS : tst_qquickpixmapcache::single(remote)
PASS : tst_qquickpixmapcache::single(remote)
PASS : tst_qquickpixmapcache::parallel(local)
PASS : tst_qquickpixmapcache::parallel(remote)
PASS : tst_qquickpixmapcache::parallel(remoteagain)
PASS : tst_qquickpixmapcache::parallel(remotecopy)
PASS : tst_qquickpixmapcache::parallel(remotecopycancel)
PASS : tst_qquickpixmapcache::massive()
PASS : tst_qquickpixmapcache::cancelcrash()
PASS : tst_qquickpixmapcache::shrinkcache()
PASS : tst_qquickpixmapcache::networkCrash()
PASS : tst_qquickpixmapcache::lockingCrash()
FAIL! : tst_qquickpixmapcache::uncached() Compared values are not the same
Actual (img.pixel(0,0)) : 4278190335
Expected (qRgb(255, 0, 255)): 4294902015
Loc: [/usr/src/debug/qtdeclarative/6.3.0-r0/git/tests/auto/quick/qquickpixmapcache/tst_qquickpixmapcache.cpp(455)]

in webOS, QQuickPixmap::Cache is always used.
https://codereview.qt-project.org/c/qt/qtdeclarative/+/308706