[feat]: change erasure coding default block size from 10MiB to 1MiB (#11721)

major performance improvements in range GETs to avoid large
read amplification when ranges are tiny and random

```
-------------------
Operation: GET
Operations: 142014 -> 339421
Duration: 4m50s -> 4m56s
* Average: +139.41% (+1177.3 MiB/s) throughput, +139.11% (+658.4) obj/s
* Fastest: +125.24% (+1207.4 MiB/s) throughput, +132.32% (+612.9) obj/s
* 50% Median: +139.06% (+1175.7 MiB/s) throughput, +133.46% (+660.9) obj/s
* Slowest: +203.40% (+1267.9 MiB/s) throughput, +198.59% (+753.5) obj/s
```

TTFB from 10MiB BlockSize
```
* First Access TTFB: Avg: 81ms, Median: 61ms, Best: 20ms, Worst: 2.056s
```

TTFB from 1MiB BlockSize
```
* First Access TTFB: Avg: 22ms, Median: 21ms, Best: 8ms, Worst: 91ms
```

Full object reads however do see a slight change which won't be
noticeable in real world, so not doing any comparisons

TTFB still had improvements with full object reads with 1MiB

```
* First Access TTFB: Avg: 68ms, Median: 35ms, Best: 11ms, Worst: 1.16s
```

v/s

TTFB with 10MiB
```
* First Access TTFB: Avg: 388ms, Median: 98ms, Best: 20ms, Worst: 4.156s
```

This change should affect all new uploads, previous uploads should
continue to work with business as usual. But dramatic improvements can
be seen with these changes.

cmd/erasure_test.go

@@ -52,7 +52,7 @@ func TestErasureEncodeDecode(t *testing.T) {
 		buffer := make([]byte, len(data), 2*len(data))
 		copy(buffer, data)
 
-		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.parityBlocks, blockSizeV1)
+		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.parityBlocks, blockSizeV2)
 		if err != nil {
 			t.Fatalf("Test %d: failed to create erasure: %v", i, err)
 		}