Do Not Output Trailing Zeros for Decimal Types in ClickHouse

Do not output trailing zeros in text representation of Decimal types. Example: 1.23 will be printed instead of 1.230000 for decimal with scale 6. This closes #15794. It may introduce slight incompatibility if your applications somehow relied on the trailing zeros. Serialization in output formats can be controlled with the setting output_format_decimal_trailing_zeros. Implementation of toString and casting to String is changed unconditionally. #27680 (alexey-milovidov).