validation: drop maximum -dbcache

Fixes #28249

src/qt/forms/optionsdialog.ui

@@ -105,7 +105,7 @@
          <item>
           <widget class="QLabel" name="databaseCacheLabel">
            <property name="toolTip">
-            <string extracomment="Tooltip text for Options window setting that sets the size of the database cache. Explains the corresponding effects of increasing/decreasing this value.">Maximum database cache size. A larger cache can contribute to faster sync, after which the benefit is less pronounced for most use cases. Lowering the cache size will reduce memory usage. Unused mempool memory is shared for this cache.</string>
+            <string extracomment="Tooltip text for Options window setting that sets the size of the database cache. Explains the corresponding effects of increasing/decreasing this value.">Maximum database cache size. Make sure you have enough RAM. A larger cache can contribute to faster sync, after which the benefit is less pronounced for most use cases. Lowering the cache size will reduce memory usage. Unused mempool memory is shared for this cache.</string>
            </property>
            <property name="text">
             <string>Size of &amp;database cache</string>

src/qt/optionsdialog.cpp

@@ -93,8 +93,7 @@ OptionsDialog::OptionsDialog(QWidget* parent, bool enableWallet)
     ui->setupUi(this);
 
     /* Main elements init */
-    ui->databaseCache->setMinimum(nMinDbCache);
-    ui->databaseCache->setMaximum(nMaxDbCache);
+    ui->databaseCache->setRange(nMinDbCache, std::numeric_limits<int>::max());
     ui->threadsScriptVerif->setMinimum(-GetNumCores());
     ui->threadsScriptVerif->setMaximum(MAX_SCRIPTCHECK_THREADS);
     ui->pruneWarning->setVisible(false);