Update Soroban settings files for SLP-0001 (stellar#4571)

# Description

Update Soroban settings files for
https://github.com/stellar/stellar-protocol/blob/master/limits/slp-0001.md.
This maintains the 5 to 1 ratio between ledger and tx settings.

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Describe what this pull request does, which issue it's resolving
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# Checklist
- [ ] Reviewed the
[contributing](https://github.com/stellar/stellar-core/blob/master/CONTRIBUTING.md#submitting-changes)
document
- [ ] Rebased on top of master (no merge commits)
- [ ] Ran `clang-format` v8.0.0 (via `make format` or the Visual Studio
extension)
- [ ] Compiles
- [ ] Ran all tests
- [ ] If change impacts performance, include supporting evidence per the
[performance
document](https://github.com/stellar/stellar-core/blob/master/performance-eval/performance-eval.md)

soroban-settings/pubnet_phase6.json

@@ -0,0 +1,29 @@
+{
+  "updated_entry": [
+    {
+      "contract_ledger_cost_v0": {
+        "ledger_max_read_ledger_entries": 500,
+        "ledger_max_read_bytes": 500000,
+        "ledger_max_write_ledger_entries": 250,
+        "ledger_max_write_bytes": 143360,
+        "tx_max_read_ledger_entries": 100,
+        "tx_max_read_bytes": 200000,
+        "tx_max_write_ledger_entries": 50,
+        "tx_max_write_bytes": 132096,
+        "fee_read_ledger_entry": 6250,
+        "fee_write_ledger_entry": 10000,
+        "fee_read1_kb": 1786,
+        "bucket_list_target_size_bytes": 14500000000,
+        "write_fee1_kb_bucket_list_low": 8510,
+        "write_fee1_kb_bucket_list_high": 12116,
+        "bucket_list_write_fee_growth_factor": 5000
+      }
+    },
+    {
+      "contract_events_v0": {
+        "tx_max_contract_events_size_bytes": 16384,
+        "fee_contract_events1_kb": 10000
+      }
+    }
+  ]
+}

soroban-settings/testnet_settings_upgrade.json

@@ -13,13 +13,13 @@
     },
     {
       "contract_ledger_cost_v0": {
-        "ledger_max_read_ledger_entries": 200,
+        "ledger_max_read_ledger_entries": 500,
         "ledger_max_read_bytes": 500000,
-        "ledger_max_write_ledger_entries": 125,
+        "ledger_max_write_ledger_entries": 250,
         "ledger_max_write_bytes": 143360,
-        "tx_max_read_ledger_entries": 40,
+        "tx_max_read_ledger_entries": 100,
         "tx_max_read_bytes": 200000,
-        "tx_max_write_ledger_entries": 25,
+        "tx_max_write_ledger_entries": 50,
         "tx_max_write_bytes": 132096,
         "fee_read_ledger_entry": 6250,
         "fee_write_ledger_entry": 10000,
@@ -37,7 +37,7 @@
     },
     {
       "contract_events_v0": {
-        "tx_max_contract_events_size_bytes": 8198,
+        "tx_max_contract_events_size_bytes": 16384,
         "fee_contract_events1_kb": 10000
       }
     },