fix: Use picker for iris grid partition selector (#2012)

Resolves #1970

**Changes Implemented:**
- Replace TableDropdown with Picker for the Partition Selector for Iris
Grid
- Change corresponding test, since role is no longer "combobox"

**Testing Information:**

Code used:
```
from deephaven import empty_table
t = empty_table(15000).update(["x = i", "y = i"]).partition_by(["x"]) 
```

Sample visual of new Picker:

![image](https://github.com/deephaven/web-client-ui/assets/69530774/1b08571f-9c25-4488-83b4-042ae3de09ca)

packages/iris-grid/src/IrisGridPartitionSelector.test.tsx

@@ -46,8 +46,10 @@ it('should display multiple selectors to match columns', () => {
     irisGridTestUtils.makeColumn('a'),
     irisGridTestUtils.makeColumn('b'),
   ];
-  const component = makeIrisGridPartitionSelector(makeModel(columns));
+  const { container } = makeIrisGridPartitionSelector(makeModel(columns));
 
-  const selectors = component.getAllByRole('combobox');
+  const selectors = Array.from(
+    container.getElementsByClassName('column-selector')
+  );
   expect(selectors).toHaveLength(2);
 });

packages/iris-grid/src/IrisGridPartitionSelector.tsx

@@ -1,10 +1,10 @@
 import React, { Component } from 'react';
 import memoizee from 'memoizee';
 import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
-import { Button } from '@deephaven/components';
+import { Button, ItemKey } from '@deephaven/components';
 import { vsChevronRight, vsMerge, vsKey } from '@deephaven/icons';
 import Log from '@deephaven/log';
-import { TableDropdown } from '@deephaven/jsapi-components';
+import { Picker } from '@deephaven/jsapi-components';
 import type { dh } from '@deephaven/jsapi-types';
 import { TableUtils } from '@deephaven/jsapi-utils';
 import { assertNotNull, Pending, PromiseUtils } from '@deephaven/utils';
@@ -294,23 +294,32 @@ class IrisGridPartitionSelector extends Component<
     const { model, partitionConfig } = this.props;
     const { isLoading, partitionFilters, partitionTables } = this.state;
 
-    const { mode, partitions } = partitionConfig;
+    const { partitions } = partitionConfig;
 
+    if (partitionFilters !== null && partitionTables !== null) {
+      partitionFilters.forEach((filter, index) => {
+        partitionTables[index].applyFilter(filter as dh.FilterCondition[]);
+      });
+    }
     const partitionSelectors = model.partitionColumns.map((column, index) => (
       <div key={`selector-${column.name}`} className="column-selector">
-        <div className="column-name">{column.name}</div>
-        <TableDropdown
-          className="custom-select-sm"
-          table={partitionTables?.[index]}
-          column={partitionTables?.[index]?.columns[index]}
-          filter={partitionFilters?.[index]}
-          onChange={this.getCachedChangeCallback(index)}
-          selectedValue={mode === 'partition' ? partitions[index] : undefined}
-          disabled={
-            (index > 0 && partitionConfig.mode !== 'partition') || isLoading
-          }
-          formatValue={this.getCachedFormatValueCallback(index)}
-        />
+        {partitionTables?.[index] && (
+          <Picker
+            label={column.name}
+            labelPosition="side"
+            table={partitionTables[index]}
+            direction="bottom"
+            shouldFlip={false}
+            keyColumn={partitionTables[index].columns[index].name}
+            placeholder={'Loading...' as string}
+            labelColumn={partitionTables[index].columns[index].name}
+            onChange={this.getCachedChangeCallback(index)}
+            defaultSelectedKey={partitions[index] as ItemKey}
+            isDisabled={
+              (index > 0 && partitionConfig.mode !== 'partition') || isLoading
+            }
+          />
+        )}
         {model.partitionColumns.length - 1 === index || (
           <FontAwesomeIcon icon={vsChevronRight} />
         )}
@@ -321,7 +330,6 @@ class IrisGridPartitionSelector extends Component<
         <div className="table-name">Partitioned Table</div>
         <div className="partition-button-group">
           <Button
-            className="btn-sm"
             onClick={this.handleKeyTableClick}
             kind="inline"
             tooltip="View keys as table"
@@ -332,7 +340,6 @@ class IrisGridPartitionSelector extends Component<
             Keys
           </Button>
           <Button
-            className="btn-sm"
             onClick={this.handleMergeClick}
             kind="inline"
             tooltip="View all partitions as one merged table"